June 23, 2008
Lawrence W. Roffee
Executive Director
U.S. Architectural and Transportation Barriers
Compliance Board
1331 F Street, N.W., Suite 1000
Washington, D.C. 200041111
Reference: Fed. Reg. Vol. 71 No. 27 Page 38563
Docket No. 20041
Americans with Disabilities Act (ADA)
Accessibility Guidelines for Passenger Vessels
Dear Mr. Roffee:
On November 13, 2006, the International Council of Cruise Lines (now the Cruise Lines International Association – CLIA) submitted comments to the referenced docket. One of the comments contained in that submittal indicated that ICCL had contracted for a professional economic impact analysis to be performed with regards to the scoping requirements for accessible cabins and other access elements. Unfortunately, as discussed with the Board, due to a personal emergency on the part of the economist conducting the study and preparing the report, the study has just now been finalized and made ready for submission. This report and amplifying documents are attached for your review and consideration. Mr. Tom Gray, the economist conducting the study will be available for discussion of his work and its conclusions.
Based on the results of the attached Access Scoping Economic Impact Study, CLIA recommends that the scoping for accessible cabins on cruise ships be placed at 2% of the guest cabin inventory.
The study was based upon two separate data bases. The first data base covers 45 ships during the year 2005 and provides information on the use of accessible and nonaccessible cabins by individuals using wheelchairs and scooters. For each ship, there is data for every voyage during 2005, for a total of more than 2200 voyages. More than 3,700,000 people traveled on these voyages. This represents a major sample of all people cruising from U.S. ports during 2005, which totaled more than 9.7 million cruise vacationers.
A second data base was developed for a sample of 15 to 20 ships utilizing data from seven years (2000 through 2006) of operating reports. An operating report is prepared by the crew on each ship for each voyage that includes information about passengers with special needs so that the crew can provide special assistance. The data base includes data on more than 9,000 voyages and approximately 15,000,000 passengers. The ships included in the longitudinal data base represent between 15 and 20 percent of total passengers originating from North American ports over the seven year period. This too is a statistically significant data base. This data base facilitates the study of the growth of need for accessible cabins over time.
Conclusions from the study are summarized as follow:
 The evidence from the seven years of existing data shows that usage rates by individuals in wheelchairs have been growing, although the data for the last three years indicate that the rate of growth has slowed considerably.
 A typical accessible cabin uses approximately 50 percent more space than a standard nonaccessible cabin. Two accessible cabins, therefore, encumber as approximately much deck space as three standard cabins.
 Wheelchair users are defined as anyone who uses a wheelchair during the cruise, whether they use the wheelchair full time, or just for distance travel. Individuals in the latter category often do not need, request, or even want an accessible cabin. Almost 70% of wheelchair users use nonaccessible cabins. Therefore, approximately 70 percent of the people using wheelchairs appear to have either a preference for nonaccessible cabins or a willingness to accept and use a nonaccessible cabin.
 Although the actual number of wheelchairs coming onboard may equal 1.9% of the cabins, the actual use of accessible cabins by wheelchair users never exceeded 0.31%. The clear implication is that if accessible cabins are used only by those that need them, then 0.5% scoping would be adequate for the “immediate” future and a 1% scoping would provide a 95% confidence level that a cabin would be in the inventory for each person needing such accommodation.
 If as many as 60 percent of the passengers using wheelchairs in 2005 used accessible cabins, then a scoping level of two percent would still be sufficient to meet the demand for accessible cabins for the next 30 years.
 Given that CLIA members are, in general, already building new ships using a 2% scoping for accessible cabins, it is clear that this the industry norm will provide an adequate number of accessible cabins for virtually 100% of demand, for those that actually are in need of them for the next approximately 35 years. Group travel may exceed this number just as it may exceed any number of accessible rooms in any hotel or other accommodation ashore. If only those that actually require these cabins use them, then 2% scoping is seen to provide for actual need well beyond 35 years.
 Using a 2% scoping for accessible cabins, the issue then becomes assuring that the cabins are not booked by those who are not in need of an accessible cabin and who are just looking for the additional space for their personal convenience. This matter has been discussed with the Department of Transportation under the auspices of their proposed rule for passenger vessel operators carrying persons with disabilities.
 It is clear that the answer to the matter in item 6 above is not to penalize the industry by requiring additional scoping that would also be used by those that are not in need, but rather to assure somehow, that the accessible cabins are available to those who need them. One way would be to require a positive affirmation of need when an accessible cabin is booked. It remains unclear as to whether or not this can be accomplished.
 Each cabin is expected to generate $140,000 per year in revenue. A cabin that is lost produces no revenue. The present value of the lost cabin revenue (using fleetwide projections) over 30 years, assuming a one percent scoping level is slightly more than $1.5 Billion.
 Given the willingness of the cruise industry to build to a 2% scoping for accessible cabins, a requirement for an additional 1% scoping of this element (to 3%) is seen to be unjustified and would result in an approximate $1.3 BILLION loss to the industry over the next 30 years. See chart 8.
The study also looked at the actual use of TTY kits. Based on actual use, CLIA recommends that no more than three TTY kits be required to be carried on each ship. Cruise operators, when provided sufficient advance notice of groups traveling onboard that may need this access element, are able to contract for additional kits and spares to meet these circumstances. Additionally, we note that TTY technology is old and almost out of date. New, more reliable, transportable and personal communications technology is being used extensively. CLIA suggests that accommodating for these newer technologies will provide much more useable communications access.
In summary, CLIA recommends that a 2% scoping requirement be adopted for accessible cabins and that no more than three TTY kits be required on each ship with additional units being available from shore resources as group booking may warrant.
We would be pleased to work with Mr. Gray, to meet with you and your staff to provide a thorough review of this work, discuss its major points and answer any questions. Please do not hesitate to contact me directly to schedule such a meeting; (703) 5164157 begin_of_the_skype_highlighting (703) 5164157end_of_the_skype_highlighting.
Sincerely;
T. E. Thompson
Senior Vice President, Technical
and Regulatory
Cruise Lines International Association
Attachments:
 Table 1 – Extract of Master File 2005
 Chart 1A  Number of Voyages by Number of Wheelchairs per Voyage for One Ship, 2005
 Table 2  Abstract of Sample Master Spreadsheet 2005 Data
 Chart 1  Number of Passengers in Wheelchairs as Percent of Total Number of Passengers, 20002006
 Chart 2  Wheelchair Users in Accessible Cabins and in NonAccessible Cabins as a Percent of Total Wheelchair Users, 2005
 Chart 3  Percent of Passengers using WC and Percent of Passengers in Accessible Cabins Using Wheelchairs as a Percent of Total
 Chart 4  Projected Growth in Wheelchair Usage Rate as a Percent of Total Passengers 20002039
 Chart 5  "Projected Accessible Cabin Usage Rate 20002039
 Table 3  Mean and Standard Deviation (SD) for the Number of Wheelchairs Onboard for a Sample of 5 Ships for all Voyages During Calendar Year 2005
 Chart 6  Number of Voyages Within a Given Range of the Mean Number of Passengers Using Wheelchairs for a Sample of Voyages 2005
 Table 4  Revenue Loss in 2005 at Various Accessible Cabin Scoping Levels
 Chart 7  Annual Loss of Revenue Over a 30 Year Period due to Scoping Requirements, Assuming 3% Annual Increase in # of Cabins and 3% Growth in Revenue per Cabin 2005 2034
 Chart 8  Present Value of 30 Year Revenue Loss at Various Cabin Scoping Levels, and a 6% Discount Rate
 Chart 9  Percent of 1511 Voyages Reporting Use or NonUse of TTY Kits 2005
PASSENGER VESSEL ACCESS GUIDELINES
ACCESS SCOPING ECONOMIC IMPACT STUDY
INTRODUCTION
This report was prepared by Mr. Thomas Gray1 in response to the request from the US Access Board for information on the impact of this rule development on the economic health of the cruise industry. It was prepared at the request of the International Council of Cruise Lines (now the Cruise Lines International Association) to examine use of accessible elements onboard cruise ships, namely accessible cabins and TTY usage and to determine the economic impact on the industry related to the scoping requirements of these elements.
Part of the preparation for cruising is the gathering of information about the special needs of passengers. This information is requested during the reservation process and is augmented by additional information obtained upon boarding the ship. Operating reports are prepared to enable the crew to augment equipment in cabins being used by individuals with special needs. Information about individuals with mobility or other disabilities is used to alert the crew to situations where additional help may be needed in response to an emergency situation. The special needs information is also used in completing the “Souls on Board” report required by the International Convention, Safety of Life at Sea (commonly abbreviated as SOLAS), for every cruise. (SOLAS Chapter III section B Regulation 27: “Details of persons who have declared a need for special care or assistance in emergency situations shall be recorded and communicated to the master prior to departure.”)
Because every cruise line has an operating report system covering passengers with special needs, the industry is better positioned than other industries to capture information regarding actual need and usage of its ships by passengers with mobilityrelated disabilities or with communicationsrelated disabilities.2 For more than two years, cruise line companies compiled data base for use in this statistical analysis.
Two major data files have been developed. The first data base covers 45 ships during the year 2005 and provides information on the use of accessible and nonaccessible cabins by individuals using wheelchairs and scooters. For each ship, there is data for every voyage during 2005, for a total of more than 2200 voyages. More than 3,700,000 people traveled on these voyages. This represents a major sample of all people cruising from U.S. ports during 2005, which totaled more than 9.7 million cruise vacationers.
Including all voyages during 2005 for the ships in the sample makes it possible to note any seasonal variation which may exist in usage rates by individuals with mobility disabilities. The data on the operating reports was input into the 2005 data base through transfer to a worksheet, a small sample of which is shown below.
Table 1, “Extract of Master File 2005”
x  x 
x  x 
A second data base was developed for a sample of 15 to 20 ships utilizing data from seven years (2000 through 2006) of operating reports.3 An operating report is prepared by the crew on each ship for each voyage. The operating report includes information about passengers with special needs so that the crew can provide special assistance for a particular passenger. The data base includes data on more than 9,000 voyages and approximately 15,000,000 passengers. The ships included in the longitudinal data base represent between 15 and 20 percent of total passengers originating from North American ports over the seven year period. This data base facilitates the study of the growth of need for accessible cabins over time. The evidence from the seven years of existing data shows that usage rates by individuals in wheelchairs have been growing, although the data for the last three years indicate that the rate of growth has slowed considerably.4
One issue for scoping the number of accessible cabins is when to install a new accessible cabin. This is a complex decision. A typical accessible cabin uses approximately 50 percent more space than a standard nonaccessible cabin.5 Two accessible cabins, therefore, encumber as much deck space as three standard cabins – sometimes more. For every two accessible cabins that are added, three standard cabins must be removed, for a net loss of one standard cabin. If a cabin disappears, it can never be sold and it can never produce revenue. Assuming that a cruise ship normally sails with all cabins sold then income6 will fall because the total number of cabins has been reduced. Assuming that the two new accessible cabins are sold to persons with mobility disabilities who need an accessible cabin, the addition of accessible cabins is justified and the industry will bear the loss of income from the lost cabin. But when the number of accessible cabins provided exceeds those requested by individuals using wheelchairs, scooters or other mobility aids, the excess accessible cabins are sold to passengers without a mobilityrelated disability. This maintains the income from the accessible cabins, but the income formerly produced by the third standard cabin originally in this space is still lost completely.
The lost cabin is generating a decline in revenue on every voyage for the life of the ship. These factors indicate that a new accessible cabin should not be added unless there is a real and continuing need for it at the time of installation.
THE DATA
The introduction contained a copy of a brief abstract from the Master File from the 2005 Data Base. The information in each line of the abstract is focused primarily on the number of passengers and the number of passengers using wheelchairs. The abstract shows the total number of cabins and the number of accessible cabins available.7 Perhaps the two most important columns in the abstract are the two which identify the number of wheelchair accessible cabins occupied by wheelchair users and the number of nonaccessible cabins occupied by wheelchair users. The abstract shows clearly what the total Master File shows: Most people using wheelchairs do not request or use an accessible cabin. This may have important implications for the number of accessible cabins needed, as will be explored in more detail below. Wheelchair users are defined as anyone who uses a wheelchair during the cruise, whether they use the wheelchair full time, or just for distance travel. Individuals in the latter category often do not need, request, or even want an accessible cabin. For this study, data was provided regarding users of wheelchairs and powered scooters. When a “wheelchair user” is referenced, it is meant to include both.
The last two columns in the Abstract identify the number of TTY kits available on each ship and each voyage, and the number of TTY kits actually used on each voyage. Note that only one voyage out of 13 voyages shows any use of a TTY kit. The implications of this ratio will be discussed in more detail later.
Moving From A Master File to a Master Spreadsheet
The Master File is basically raw data for each ship and each voyage in the 2005 Data Base. In order to explore the implications of this data, a Master Spreadsheet was developed for each ship in the 2005 sample. The abstract of the Master Spreadsheet below shows the data for approximately half the ships in the sample. The totals shown at the bottom of each column in the abstract are the total for the whole data base and not for the subsample shown in the abstract. The number of voyages per year is a function of the length of voyage on each of a given ship’s itineraries.8 Note that the number of cabins is shown only as more than 1000 (> 1000) or less than 1000 (< 1000). The number of accessible cabins available is shown in the next column. The annual number of wheelchair users in accessible cabins and the annual number of wheelchair users in nonaccessible cabins are shown in the next two columns, with the sum of the two columns shown in the column marked Total WC. The total number of passengers on board each ship is shown in the next column. Note that the number of passengers in the Data Base is 3,708,359.9 This number can be compared to the total number of passengers using wheelchairs, 16,779, to the total number of passengers in accessible cabins using a wheelchair which equals 5,619 and to the total number of passengers originating in 2005 from North American ports of approximately 9,700,000.
A Brief Aside—Examining the Data for One Ship in the 2005 Sample
Modern economic analysis is often based on complex statistics generated using mathematical formulas. It is also possible to understand the importance of these statistics by examining the basic data in its raw form. One way to do this is to examine one ship and the cruises it made during 2005. The ship is selected at random from the ships available in the 2005 sample. The ship made 74 cruises (each cruise being four or five days in length) during the course of the year. Some passengers used wheelchairs during each voyage, with a low number of two users on three voyages and a high of 19 users on one voyage. The average number of wheelchair users on board was 7.710 In addition to the mean or average number of wheelchairs on board, we also need a measure of the variance around this number. This is done by comparing the actual number of wheelchairs on a given voyage to the mean number for all of the voyages during the year. We sum the results and divide by the number of voyages. To eliminate negative numbers we first square the differences between the average and the actual number for each voyage, sum over all of the voyages and divide by the number of voyages. We then take the square root of the result and call this the Standard Deviation. In the case of the ship we are examining, the standard deviation is equal to 3.5.11
With the mean value (the average number of wheelchairs on the 74 voyages of the sample ship) and the standard deviation (or measure of dispersion of these values around the mean) we can now characterize the distribution. The shape of the distribution is shown in Chart 1A.
Chart 1A, “Number of Voyages by Number of Wheelchairs per Voyage for One Ship, 2005”
Note that the number of voyages is shown on the vertical axis. There were 0 voyages with only one wheelchair on board. This is shown by the zero resting on the x axis number 1. There were three voyages with only two wheelchairs on board and four voyages with three wheelchairs on board. The number of voyages with five and six wheelchairs on board jumps to 10 and 11 voyages respectively. The number of voyages falls somewhat for voyages with seven and eight wheelchairs and then jumps to 12 voyages with nine wheelchairs on board. The number of voyages with 12 or more wheelchairs falls to only one or zero, except for 17 and 19 wheelchairs per voyage which each occur once.
In looking at the chart for the distribution, the reader may see a resemblance to the normal distribution or “bellshaped” curve which describes many of the distributions observed in the world. Note that the distribution is centered relatively close to the mean value of 7.7 wheelchairs per voyage. One feature of the standard distribution is that we know a great deal about it. We can, for example, calculate the confidence interval around the mean. The confidence interval can be set at any level but is usually quoted at the 95 percent confidence level. Rather than define the distribution in terms of the mean and standard deviation, we define the confidence interval such that 95 percent of the observed numbers of wheelchairs per voyage will fall within the confidence interval. It turns out that the confidence interval is equal to the mean value plus or minus 1.96 times the standard deviation. For our sample ship the confidence level is equal to 7.7, the mean value plus or minus 1.96 times 3.5, the standard deviation. This says that we expect 70 of our 74 voyages to be within the range 0.7 wheelchairs to 14.7 wheelchairs.12 Looking at the chart, it turns out that 70 voyages are within the 95 percent confidence interval and only four voyages are outside this interval. It appears that the distribution of wheelchairs per voyage is a normal distribution. Another way of saying this is that 19 out of 20 times we expect the number of wheelchairs on board ship to be within our 95 percent confidence level. If we set the number of accessible cabins to meet the numbers found within this range, we can expect to meet the needs of individuals using wheelchairs 95 percent of the time
The statement above needs to be adjusted. The 95 percent confidence level is defined to include the distribution closest to the mean value, leaving out the positive and negative tails of the distribution. In terms of providing accessible cabins, however, we don’t need to worry about very small numbers of wheelchairs. If we use the mean value or the mean plus two standard deviations as the base for estimating the number of wheelchair accessible cabins, there will be excess capacity whenever we have very small numbers of wheelchairs on board. Therefore, any numbers of wheelchairs in the negative tail of the distribution are not a problem. If we use the mean plus 1.96 times the standard deviation to define the upper limit of the confidence level, then the number of accessible cabins will be sufficient at the 97.5 percent level of confidence. This level applies to all wheelchair users, assuming that all wheelchair users ask for accessible cabins.
But the experience with the ships in the 2005 sample says that only about 30 percent of the individuals using wheelchairs use accessible cabins. Defining the number of accessible cabins using the mean plus two standard deviations as the base for all wheelchair users would, therefore, vastly overstate the number of wheelchair users using such cabins.13 In a typical situation using just the mean or average number of wheelchairs as a base for the number of accessible cabins would overstate the actual usage as measured in 2005.
To overcome any lingering doubts that the number of wheelchairs is normally distributed, the reader can examine Table 3, below, which provides similar data for five ships, and look at Chart 6, below, which shows the distribution for all of the ships and the 2200 plus voyages in the 2005 data base. In Chart 6, fewer than one percent of the observations lie outside the confidence interval defined by the mean plus or minus 2 standard deviations.
Table 2, “Abstract of Sample Master Spreadsheet, 2005 Data”
x  x 
x  x 
Returning to our description of the Master File, the next set of columns (Columns I, J and K) calculates three ratios which provide information about the probability of a passenger using a wheelchair on a ship. The first ratio is the ratio of total wheelchair users to total passengers. For the first ship in the subsample, the ratio is 0.0045. This can be read as “For each 1000 passengers, 4.5 passengers will be using a wheelchair.” Since fractional people don’t exist, it makes more sense to say that “approximately one half of one percent of the people use a wheelchair during their sailing.” Note that there is some difference between ships, with a high ratio of 0.73% on one ship and a low ratio of 0.14% on another. Most ships are clustered fairly close to the 0.5% level, however.14
The next column (Column L) shows the ratio of wheelchair users in accessible cabins to total passengers. As might be expected, this ratio is very low on most ships, since wheelchair users in accessible cabins represent a minority of total wheelchair users on every ship. This ratio never exceeds 0.31% and in most ships is much smaller than this value. The third ratio shows the ratio of total wheelchairs to total cabins available. This ratio is usually under 0.1% for most ships but it does reach as high as 1.92% in one case and 1.90 in a second case. These two cases are ships that focus on long voyages of more than 10 days. There is a correlation between length of voyage and number of wheelchairs used: The longer the trip, the higher the proportion of wheelchair use. However, once again, although the actual number of wheelchairs coming onboard may equal 1.9% of the cabins, the actual use of accessible cabins by wheelchair users never exceeds 0.31%. The clear implication is that if accessible cabins are used only by those that need them, then 0.5% scoping would be adequate for the immediate future.
In the next set of four columns (Columns M, N, O, and P) the number of accessible cabins required is calculated based on the “total wheelchair to total cabins available” times the number of cabins on the ship. This number usually results in a whole number plus a fraction. For the first ship in the list, for example, the number of cabins required to meet the average usage of wheelchairs over the 47 voyages this ship made in 2005 is 7.51. Since the concept of a fractional cabin has no meaning, the calculated number is rounded up to the nearest whole number above seven, in this case eight cabins. To get a feel for where this number of cabins fits relative to possible scoping levels, the next three columns indicate the number of cabins needed to equal 1%, 2%, or 3% of total cabins. So far, for ship number one the conclusion is that, on average, eight cabins would have been sufficient to provide everyone using a wheelchair with an accessible cabin.15
Moving to the column (Column Q) to the right of the 3% column, the ratio of wheelchair users in accessible cabins to total wheelchair users is calculated. From this ratio we can calculate the number of accessible cabins needed to meet the average need for such cabins in 2005. Since approximately 60 % of people using wheelchairs on this ship did not use an accessible cabin, the number of cabins must be lower than the 7.51 (8) cabins needed to meet the needs of all wheelchair users. In fact only 3.04 wheelchair accessible cabins would be sufficient to meet the needs of the average number of individuals using accessible cabins on this ship. Since the 3.04 cabins must be rounded up to four cabins, then four cabins should be adequate for most voyages on this ship. This means that ½ of one percent of total cabins would need to be accessible to meet the typical need for accessible cabins at the usage rate experienced in 2005. Looking at the last column (Column U) on the right hand side of the chart, the number of accessible cabins needed to meet the average need for accessible cabins is shown for each ship in the subsample. In almost all cases the percentage of total cabins needed is less than 0.5%, although one ship does reach 0.625 percent. For the whole sample, the average proportion of total cabins needed to meet the actual usage of accessible cabins in 2005 is 0.35%, or 1/3rd of one percent. This is considerably below the proposed scoping level of 3% of total cabins as accessible cabins.
Several factors have already been identified which may serve to increase the need for accessible cabins over time. These include continued growth in the population using wheelchairs on a full time basis, variance in need for accessible cabins on different voyages, seasonal variation, etc. These factors will be examined more intensively in the sections which follow.
USING THE LONGITUDINAL DATA BASE TO EXAMINE GROWTH AND CHANGE IN NEED OVER TIME
One of the columns in the Master Spreadsheet just examined calculated the ratio of passengers in wheelchairs to the total number of passengers. The longitudinal data base developed for a sample of 15 to 20 ships can be used to examine the growth in the use of wheelchairs on cruise ships. The data presented in the chart below is for the years from 2000 through the first half of 2006, or a total of seven periods. Although there is complete data for all of the years from 2000 through 2005, only the first half of the year is used for each year’s observation. This allows us to add the 2006 halfyear period to our data points. There is a seasonal variation between the first half of the year, with wheelchair usage rates slightly higher during the summer months and over the Thanksgiving, Christmas, and New Year’s holidays. The variance between the first half of the year and the second half is not sufficient to produce a significant change in the data or in the conclusions to be reached from an examination of the data.16 The data are shown in Chart 1, labeled “Number of Passengers in Wheelchairs as Percent of Total Number of Passengers 2005.”
Chart 1 “Number of Passengers in Wheelchairs as Percent of Total Number of Passengers, 20002006”
The year 2000 corresponds to point 1 on the x axis of the chart, with the year 2006 at point 7 on the x axis. Note that the average wheelchair usage increased at a rapid rate from 2000 through 2001, 2002, and 2003. Growth continued through 2004, although at a time when more accessible cabins are available in the inventory due to the number of new ships that have come into service, at a slower pace than in the earlier years. From 2004 to 2005 growth slowed almost to zero and in 2006 the growth rate turned negative. This actual experience from large samples of ships and passengers (two to three million passengers per year in the sample) does not meet expectations that aging baby boomers are retiring now and sailing much more frequently than in the past. While more aging individuals are sailing, even more, younger individuals are choosing to cruise in recent years.
The major point to be taken from this chart is that the need for cruising on the part of people using wheelchairs has not always risen in the past, and may not rise in the future. The fact that more people within the general population are using wheelchairs is not sufficient to support a conclusion that wheelchair usage on cruises will continue to increase to the same extent as the use of wheelchairs increases.17
Why do Most Wheelchair Users on Cruise Ships not Request Accessible Cabins?
There may not be an obvious answer to this question, but the facts are indisputable. Chart 2, below shows wheelchair users in accessible cabins and wheelchair users in nonaccessible cabins as a percent of total wheelchair users. Almost 70% of wheelchair users use nonaccessible cabins. It may be that many of these individuals only use wheelchairs for distances onboard or in port. On board, they may find that they can reach any point of interest by walking slowly or by use of a walker, cane or crutches.
Insert Chart 2, “Wheelchair Users in Accessible Cabins and in NonAccessible Cabins as a Percent of Total Wheelchair Users, 2005”
For a person using a walker, cane, or crutches, the additional space made available in an accessible cabin may not be necessary, and, in fact, may be an inconvenience. The large space required as a turning radius for a wheelchair, for example, may lengthen the trip to the toilet or from the toilet to the lavatory. Lower furniture surfaces or lower countertops may inconvenience a person using a cane, a walker or crutches to remain upright.
In their informational brochures and on their web sites the major cruise lines make information available to prospective passengers that accessible cabins are available. Despite the widespread awareness of accessible facilities that this produces many people with mobility disabilities choose not to use accessible cabins. Some of these individuals board ship using a wheelchair, but many of them appear not to use a wheelchair once on board. Given that they should be aware that accessible cabins are available, it appears that they choose to use a nonaccessible cabin
Returning to the longitudinal data base and using the distribution of wheelchair users between accessible cabins and nonaccessible cabins from Chart 1 we can estimate wheelchair usage in nonaccessible cabins.18 The estimates are shown in Chart 3, immediately below. The top line in the chart provides the same information examined earlier which showed that from 2000 through 2006 the percent of total passengers using wheelchairs increased from 0.264 percent to 0.445 percent. The percent of passengers using wheelchairs in accessible cabins (30.2 percent of the total passengers using wheelchairs) is shown in the bottom line. Note that the percentage of passengers using wheelchairs in accessible cabins never rises above 0.15 percent and is 0.144 percent in 2006.
Chart 3 “Percent of Passengers Using WC and Percent of Passengers in Accessible Cabins Using Wheelchairs as a Percent of Total Passengers, 20002006”
The seven years of data in the longitudinal file are important since they measure the actual usage of wheelchairs in accessible and nonaccessible cabins in recent times. Perhaps a more interesting question is what this data implies about future utilization rates. The proportion of passengers using wheelchairs did increase fairly rapidly over the first four years for which we have data (20002003) but growth ceased or became negative after that (20042006). The rapid expansion between 2000 and 2003 occurred at the same time that cruising expanded rapidly in the United States. Cruising by passengers using wheelchairs grew more rapidly than growth in total passengers, howeverso the general growth in the number of people cruising can not be used to explain the rapid increase in travel by individuals using wheelchairs.
Returning to the question of what the future holds, the most frequently used technique for predicting future events is to fit a line to the existing data and project the line forward to see the implications for future levels of activity. This is done in the Chart 4, below.
Chart 4 “Projected Growth in Wheelchair Usage Rate as a Percent of Total Passengers 20002039”
The first seven points on the chart show the experience from 2000 through 2006. The remainder of the chart shows projected growth of total wheelchair use over the next 33 years. Projecting forward for thirtythree years gives us a total of 40 years. This 40year projection enables evaluation of interesting time periods ranging from 10 years through 15, 20, 25, 30, and 35 years. The growth in 2000 through 2004 has a major influence on the slope of the projected growth line since the line continues at an upward slope throughout the projection period. Note that projected wheelchair usage reaches the one percent level in the 12th year of the projection, reaches two percent in the 23rd year and reaches three percent in the 35th year of the projection.
Several issues should be noted in considering these numbers.
 First, the proposed scoping requirement for accessible cabins is three percent, but usage at the three percent level would not be reached for another 28 years. Note that this accessible cabin usage rate assumes that all individuals using wheelchairs request accessible cabins. As seen in Chart 2, above, only about 30 percent of wheelchair users actually used accessible cabins in our 2005 data base.
 Second, most cruise ships are not maintained in usage within the U.S. market for more than 20 to 25 years. After that time they are replaced by new ships and the older ships are sold off for usage in nonU. S. markets or the ships are scrapped and recycled. Taken together, these points suggest that the proposed scoping requirement is too high.
 This point is further emphasized by the third issue: What affect does the fact that a majority of wheelchair users appear to use nonaccessible cabins have on the projected growth of need for accessible cabins? It may be expected to lower the overall growth rate of need for accessible cabins as shown in the next chart.
Chart 5, “Projected Accessible Cabin Usage Rate 20002039”
There are now two projections shown. The top line is the same as shown in Chart 4. The bottom line projects growth in the need for accessible cabins, given that approximately 70 percent of the people using wheelchairs appear to have either a preference for nonaccessible cabins or a willingness to accept and use a nonaccessible cabin.19 In the 15th year of the projection, need for accessible cabins has increased to only 0.5 percent. By the end of the 25th year need has increased to almost 0.9 percent, and in the 30th year of the projection need for accessible cabins finally reaches 1.0 percent. Given this scenario, there is no apparent reason why a scoping requirement of more than one percent should be required to meet not only the current need for such cabins, but also expected future need over the first 30 years of the projection.20 All of these projections indicate that the proposed scoping requirement for accessible cabins should be changed to no more than one percent rather than the three percent specified in the current working document.
How Much Does the Need for Accessible Cabins Vary by Voyage?
What are the Implications of This Variance for Scoping Requirements?
The previous discussion was based on need averaged over many voyages, itineraries, and lengths of voyages. On any given voyage, however, need for accessible and nonaccessible cabins may vary with some voyages marked by less than normal needs and other voyages facing higher needs. Although cruise lines point out that some times of the year and some itineraries are more popular than others, warning potential passengers to seek reservations at an early date for these popular voyages, some passengers invariably wait too long and are disappointed when their desired voyage is sold out prior to their inquiry. Is the proposal of a one percent scoping requirement for accessible cabins likely to be sufficient given the possibility of higher need for accessible cabins on some voyages? The immediate followup question is how often do we face a higher need for accessible cabins? To answer this question, the 2005 sample examined more than 2000 voyages to determine what the actual number of individuals using wheelchairs was on each voyage. From this data a mean (average) number of wheelchair users was developed for each vessel. If a particular vessel sailed 50 times during the year 2005, for example we added up the total number of wheelchairs reported on each of the 50 trips and divided by 50 to get the average number of wheelchairs for a typical voyage on that ship. We counted all users of wheelchairs, whether they asked for and used an accessible cabin, or whether they asked for and used a nonaccessible cabin.
Next the standard deviation (SD) around the mean was calculated. The standard deviation measures the variance around the mean. It is the most common measure of statistical dispersion, basically providing a measure of the spread of the values in a data set. If the values around the mean are widely spread, then the standard deviation will be a larger number. Conversely, if the data points are close to the mean, then the standard deviation is closer to zero. If the standard deviations in the cruise line case are large relative to the average need for wheelchair usage, then we can expect that some voyages will face large excess needs from wheelchair users.
Table 3 immediately below shows the means and standard deviations for five ships. The first line for each ship shows the mean, the standard deviation and several ranges of standard deviations around the mean. There is only one mean for each ship, and one standard deviation. The mean and standard deviation are shown in the third and fourth columns for each ship. The columns to the right show the number of wheelchairs obtained by adding or subtracting the standard deviation to the mean to produce a range of values around the mean. For ship one, 8.7 (the mean) plus 3.7 yields 12.41. Subtracting the standard deviation of 3.7 from the mean of 8.7 yields a value of 4.99. The range of values between 4.99 and 12.41 is within plus or minus one standard deviation from the mean. Said more simply on some voyages there were between 5 and 12 passengers using wheelchairs on the ship.
The second line for each ship shows the number of voyages where the number of wheelchairs is within a particular range such as within one standard deviation above or below the mean. In the case of ship number 1, the second line shows that 74 of the 103 voyages had between 5 and 12 wheelchairs onboard. Another 15 voyages had five or fewer passengers with wheelchairs on board. There were twelve voyages with between 12.43 and 16.13 wheelchair users onboard.21 One voyage had between 16 and 20 wheelchair users onboard, and one voyage had 20 or more wheelchair users on board.
Table 3, “Mean and Standard Deviation for the Number of Wheelchairs on Board for a Sample of 5 Ships for all Voyages During Calendar Year 2005”
x  x 
x  x 
For ship # 1, on average there were 8.7 passengers using wheelchairs on each voyage. Some of these 8.7 individuals boarded using a wheelchair but did not use the wheelchair on the ship. Some of the wheelchair users chose accessible cabins; some chose nonaccessible cabins. As shown in the last column, one percent of total cabins on ship number one is equal to 11 cabins. If the ship had only 11 accessible cabins, then on at least 14 voyages it could not have accommodated in accessible cabins all of the passengers using wheelchairs, but as noted earlier almost 70 percent of individuals using wheelchairs on cruises do not use accessible cabins. Given this ratio of wheelchair users in nonaccessible cabins to wheelchair users in accessible cabins, only 30 percent of the wheelchair users on these 14 voyages would choose accessible cabins. If the highest number of wheelchair users on the one voyage where the number was more than 3 SD above the mean was 25, nine accessible cabins would have been sufficient for wheelchair users choosing accessible cabins.22
When examining the variance in need over many voyages, the use of one, two and three standard deviations is not arbitrary. In a normal situation it is expected that 68 percent of the variance will be within one standard deviation of the mean. Ninetyfive percent of the variation will be within two standard deviations from the mean and 97.5 percent will be within three standard deviations. Looking at our major sample from the year 2005, the chart below shows the variance in the number of wheelchairs found on board for more than 2000 voyages
Chart 6, “Number of Voyages within a Given Range of the Mean Number of Passengers Using Wheelchairs for a Sample of Voyages 2005”
The chart shows that most voyages (1520 out of 2209) are clustered closely within one standard deviation from the mean number of wheelchairs for each ship. Another 316 voyages show a number of wheelchairs more than one standard deviation below the mean number of wheelchairs. A number of wheelchairs this low would imply that many of the accessible cabins on this voyage would not be used by passengers using wheelchairs. Another 290 voyages show the number of wheelchairs to be greater than one standard deviations above the mean but less than two standard deviations above the mean. Notice the next two columns which show the “positive tail of the distribution” has very low numbers of voyages. Only 83 voyages out of 2209 in this sample have wheelchair numbers greater than two standard deviations above the mean.23 There is less than a one percent probability that there will be such a large number of wheelchairs on a given voyage. In general the variance in need for wheelchairs on a ship appears to be normally distributed with most voyages showing a need close to the average need for all voyages on that ship. This implies that the scoping requirement can be set close to the mean or average number of wheelchairs on a typical voyage. Given that a large percentage of people using wheelchairs on cruises choose nonaccessible cabins24 the number of accessible cabins can be adjusted downward from the one percent suggested here. This leads us back to the question of what the implications are for future growth and how growth may change the scoping requirement. Before examining this question and its economic implications in detail several questions about the size and shape of accessible cabins must be answered.
The Size of Accessible Cabins and the Implication of Size for the Number of Cabins and for Revenue from Cabin Rentals and Incidental Spending
A typical cabin to be accessible must meet the guidelines established by the Access Board, first proposed in a draft document published on November 26, 2004 and amended on July 7, 2006. These guidelines include: a wider entry door, a wider passageway into the cabin, wider open spaces next to the bed(s) in the cabin, a larger bathroom with appropriate entry and turning space for a wheelchair, restrictions on certain heights, shape of handles and other fixtures, etc. Marine architects representing a number of the lines examined these draft specifications carefully and incorporated them into a feasible design that would make a cabin fully accessible. It clearly evident that an accessible cabin, given the requirements proposed in the guidelines and as seen in actual practice, would occupy the linear space perpendicular to the center line of the ship equal to one and one/half typical nonaccessible cabins. One inescapable conclusion based on this outcome is that adding two accessible cabins is the equivalent of losing three nonaccessible cabins. This implies that for every two accessible cabins added, there will be a net loss of one cabin on the ship. This might not be that important if ships frequently travel with empty cabins. But ships rarely travel with empty cabins and the loss of a cabin means a loss of revenue on each and every voyage made by a ship.
How big is the expected loss? Turning to average passenger expenditures for the fleet active in U. S. waters, the expected income per cabin in 2005 was equal to $400 per day.25 The typical cabin is expected to be producing revenue for 350 days per year, implying that a typical cabin will produce approximately $140,000 per year. Loss of a cabin, therefore, is not a minor matter and care should be taken to establish scoping requirements for accessible cabins that are sufficient to meet the needs of individuals with mobilityrelated disabilities requiring more space, without imposing more cost than is necessary on the cruise industry.
The Dimensions of Potential Revenue Losses in the Year 2005
The dimensions of lost revenue can be examined using the table below which shows the extent of revenue losses as a function of three things:
 the number of ships presently in the industry’s collective fleet;
 the number of cabins per ship; and
 The scoping level established in the guidelines.
The revenue losses are shown for four possible scoping levels for accessible cabins, beginning with onehalf of one percent and moving to one, two, and three percent. The expected annual revenue loss is a function of the number of regular cabins lost because of the larger dimensions of accessible cabins and the number of accessible cabins as determined by the scoping requirement established in the Guidelines.
Insert Table 4, “Revenue Loss in 2005 at Various Accessible Cabin Scoping Levels”
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x  x 
The data provided in the first 23 rows of Table 4 are for 23 ships, a subset of our 2005 sample. The third column from the left shows the number of cabins lost if each ship is required to have onehalf of one percent accessible cabins. The annual revenue related to this number of accessible cabins is shown in the fourth column.26 Columns five through ten repeat the calculations for one, two, and three percent scoping. For the 23 ships shown in the top part of the table, annual losses for the first year would range from $8,960,000 for a onehalf of one percent scoping requirement to $46,480,000 for a three percent scoping requirement. The bottom three rows of the table extend the annual revenue loss estimates first to the remainder of the ships in the 2005 sample, then to the rest of the cruise line fleet and finally to the total fleet including both of the subsamples plus the rest of the fleet. With a scoping requirement for accessible cabins of onehalf of one percent, the annual loss in revenue in 2005 for the fleet would be $39,060,000. At a three percent scoping level the total annual loss for 2005 would increase to $198,240,000.
The fleet being discussed here is made up of the ships belonging to the cruise lines that are members of CLIA. Many of these ships regularly sail out of and in to U. S. ports with itineraries including visits to one or more countries outside the United States. It should be noted that the fleet size is an estimate which does not include some ships active in U. S. waters. The estimate does not include all cruise ships operating on rivers or lakes for example, assuming that these ships may not touch at a foreign port.27 The fleet does contain some ships that cruise outside of United States and rarely touch at U. S. ports. The total fleet consists of 192 ships with 225,364 total cabins.28
In preparing the estimates of total cabins lost in the fleet, it was assumed that the number of cabins lost depended on the number of embarkations in the 45 ships for which there is complete data, relative to the number of embarkations in the rest of the fleet. Although the number of ships in the sample is only 45, these ships account for approximately 45 percent of U.S. embarkations. This implies that the larger number of ships in the remainder of the fleet account for 55 percent of embarkations.
Assuming that the three percent scoping requirement for accessible cabins recommended by the Access Board is maintained, total annual revenue for the fleet would decrease by $198,240,000 in 2005. What does this imply for the industry? The revenue decrease from cruising implies a major decrease in profits. This relatively much larger decrease in profits occurs because many of the costs on a large cruise ship are fixed costs. Since the physical size of the ship has not changed, the costs of moving and operating a ship are the same even if it has X percent fewer cabins. The costs of maintenance and repair stay constant and personnel costs will stay roughly the same,29 as will a good portion of other operating costs. Most of the decrease in cabin revenue, therefore, will not be offset by decreases in costs, and the impact of the lower revenue will directly impact the industry’s bottom line.30
Note that the revenue losses being discussed in this section occur because some nonaccessible cabins are lost when the number of accessible cabins is increased. For every two additional accessible cabins added, three nonaccessible cabins will be lost, producing a net loss of one cabin. Each cabin is expected to generate $140,000 per year in revenue. A cabin that is lost produces no revenue. This is true independent of who occupies the new accessible cabins. It is important, therefore, that the number of accessible cabins be sufficient to meet the need for cabins by people with disabilities, but equally important that the available supply of accessible cabins not be much greater than the expressed need.
The cruise line industry has been adding accessible cabins as it has expanded the fleet in recent years Acknowledging that many passengers boarding with wheelchairs choose to use nonaccessible cabins, this study indicates that a one percent scoping level would provide sufficient accessible cabins for at least the next 30 years (See Chart 5). If more than 30 percent of the passengers using wheelchairs choose accessible cabins, then the one percent number will not be sufficient for the next 30 years. If, for example 60 percent of individuals using wheelchairs chose accessible cabins, then a two percent scoping level would be sufficient for the next 30 years.
Providing this level of accessible cabins costs the industry approximately $72 million per year (See Table 4). The three percent scoping requirement, if left in place according to the recommendation of the Access Board, would raise annual losses to the level of $199 million per year. The increased annual loss to the cruise line industry would not provide additional services to people with mobility related disabilities, since they appear not to need anywhere near one percent accessible cabins either now or in the next 15 to 20 years.
The effect of a “too high” scoping requirement can be traced in the next section which looks at the present value of the revenue loss over a 30 year period.
REVENUE LOSSES OVER THE EXPECTED LIFETIME OF THE FLEET AT ALTERNATIVE SCOPING LEVELS FOR ACCESSIBLE CABINS
Projecting Revenue Losses
Annual revenue losses are a function of the size of the cruise fleet, measured in total cabins available each year, and a function of the average revenue per cabin in each year. The size of the fleet for the initial year is shown in the table in the previous section. The daily revenue of $400 per cabin is also shown in the table.31 The chart below expands the information in the table above by projecting the numbers forward for the next 29 years, providing a 30 year time horizon for the examination of revenue losses due to alternative scoping requirements for accessible cabins. Two simple assumptions underline the growth projections for revenue losses: 1) the number of cabins in the fleet increases by three percent per year; and 2) the income per cabin increases by three percent per year.32 These rates appear reasonable given past experience.
Chart 7, “Annual Loss of Revenue Over a 30 Year Period due to Scoping Requirements, Assuming a 3% Annual Increase in # of Cabins and 3% Growth in Revenue per Cabin 200520034”
Given the expected positive growth in both the number of cabins and the expected growth in revenue per cabin, the loss associated with scoping levels of onehalf of one percent, one percent, two percent, and three percent will grow each year. The numbers on the vertical axis show the annual loss in revenue for each year for the four alternative scoping levels. With a scoping level of three percent, for example, the expected annual loss to the industry in revenue in year 30 is almost $500,000,000. At a two percent scoping level, the expected loss in revenue in the 30th year is $320,000,000. Note that each point on each line in the chart measures the expected annual loss for that year. The numbers are large, emphasizing why it is critical to set the scoping requirement for accessible cabins at an appropriate level that meets the needs of individuals with mobilityrelated disabilities who need additional space, without exceeding legitimately anticipated usage and therefore reducing revenues and profits unnecessarily.
When discounted to present value, the nearly $500 million in lost revenue that won’t be experienced until the 30th year will be worth less today. What does the loss of $500,000,000 in the 30th year mean today? To capture the current impact of the future stream of revenue losses we can compute a present value of the stream by discounting future amounts (including the expected $500 million loss in the 30th year) by the expected rate of interest to be encountered over the next 30 years and adding the discounted amounts. This is done in Chart 8 assuming that the annual longterm interest rate encountered over the next thirty years is six percent. The dollar amounts in the chart are all in millions, and the amounts are large. The present value of the lost cabin revenue over 30 years, assuming a onehalf of one percent scoping level is slightly more than $800 million. At a three percent scoping level the present value of the 30 year loss stream is just over $4 billion. The most important comparison of present value amounts is the comparison between the losses incurred with two percent accessible cabins and three percent accessible cabins. Chart 8 shows that maintaining the proposed scoping level at three percent of total cabins rather than two percent of accessible cabins will cost the industry more than $1.3 billion in present value. The extra losses do not increase the welfare of individuals with mobility related disabilities, since there doesn’t appear to be a need sufficient to warrant more than a one percent scoping requirement.
Chart 8, “Present Value of 30 Year Revenue Loss at Various Cabin Scoping Levels, and a 6% Discount Rate”
In addition to understanding the impact of the scoping level on revenue, it also is important to understand who benefits and who loses if scoping levels are set incorrectly. As mentioned previously, whatever scoping level for accessible cabins is established, it should be sufficient to insure that people using wheelchairs should have full access to the ships and services of the cruise industry. Traditionally, the cruise industry has welcomed all travelers. The industry has already invested millions of dollars to alter existing ships to make them more accessible, and it has designed improved accessibility into the ships now coming on line in recent years and in the future. Given the larger size required for accessible cabins, and the fact that the net number of cabins per ship will decrease, the cruise line industry is concerned that the scoping level for accessible cabins be set appropriately.
The numbers presented in the charts and tables of this paper demonstrate that a one percent scoping requirement is sufficient to meet the longterm growth in need for accessible cabins. If the scoping level is set at the now recommended three percent, a number of costs are incurred. Ignoring for a moment the sizeable cost of building or altering cabins in order to make them accessible,33 the following situation would then exist:
 The number of accessible cabins used by individuals in wheelchairs would be less than one percent over most of the 30 year period, approaching one percent as we get to the end of the period (See Chart 5)
 Three percent of cabins will be accessible, but twothirds of the accessible cabins will not be occupied by individuals using wheelchairs.
 Each ship with three percent accessible cabins will have one percent fewer total cabins than it would have if only one percent of cabins were accessible.
The scoping requirement for accessible cabins can produce much larger consequences than might be expected. These consequences have important implications for the welfare of many individuals both with disabilities and without disabilities. Properly set, the scoping requirements insure the flow of necessary services to provide accessibility to individuals with disabilities
ANOTHER SCOPING REQUIREMENT — Communication Kits
Another scoping requirement proposed by the Access Board specifies the number of cabins that must be “communications accessible” (i.e., accessible to persons with hearing disabilities). Cruise lines typically provide communications accessibility through use of portable Communication kits, which can be installed in any cabin on the ship. The industry has indicated that on many voyages these Communication units are not requested by travelers nor are they used. Storing and maintaining Communication kits on board ship takes resources and space that can be used for other purposes. The fact is that on the great majority of voyages the kits are not used. This is illustrated in the chart immediately below which shows the extent of usage of Communication kits on 1511 voyages on approximately 40 ships in the year 2005.
Chart, 9 “Percent of 1511 Voyages Reporting Use or NonUse of Communication Kits 2005”
On 83.5 percent of the 1511 voyages in the sample, no Communication kits were used. On the other 16.5 percent of the voyages at least one kit was used, although it should be noted that often more than one kit was used. Some voyages featured as many as 20, 30, and 60 Communication kits to service large groups of individuals with hearing disabilities. However, these are the exception, and when a group expresses a specific need sufficiently in advance, that need can be met through special acquisition. The fact that 85 percent of voyages had no requests for Communication kits means that maintaining large numbers of kits on every ship can be problematic. Kits may deteriorate over time, and maintenance may be difficult given the low level of usage. When the industry receives advance that special equipment must be provided for persons with special needs, the industry has shown that it can meet those needs. When communication kits are needed in any number beyond minimums, they are obtained from vendors. Thus, if kits must be retained on board, the number should be no more than three communication kits per ship.
SUMMARY OF IMPORTANT POINTS REGARDING ACCESSIBLE CABIN SCOPING
Based on the findings recorded in this study the following points are highlighted regarding scoping levels for accessible cabins:

If only 30 percent of the passengers using wheelchairs in 2005 used accessible cabins, then a scoping level of 0.5 percent (one/half of one percent) would be sufficient to meet the expected demand for accessible cabins for the next 15 years. This expected demand is based on the growth rates in the number of passengers using wheelchairs experienced from the year 2000 through the year 2006.

If only 30 percent of the passengers using wheelchairs in 2005 used accessible cabins, then a scoping level of one percent would be sufficient to meet the demand for accessible cabins for the next 30 years.

If as many as 60 percent of the passengers using wheelchairs in 2005 used accessible cabins, then a scoping level of two percent would be sufficient to meet the demand for accessible cabins for the next 30 years. While the 30 percent of wheelchair users who use nonaccessible cabins appears low, it is unclear whether the ratio would increase significantly in the future. The percentage could increase for two reasons: First, a large increase in the proportion of wheelchair users who cannot move without use of the chair, Second, a change in the preferences of individuals using wheelchairs such that a much higher proportion of wheelchair users request and use accessible cabins. Given that many accessible cabins would currently go unused because of the low proportion of people using wheelchairs who use accessible cabins, it is difficult to see the 30 percent ratio doubling to a 60 percent ratio in the future. If it did happen, however, a two percent scoping requirement would still provide more than ample capacity.

Based on these findings, a scoping level for accessible cabins be set at 2 percent would meet the social and civil rights needs of the disabled community for at least the next 30 years.
1 Mr. Gray was for many years Chief Economist for the U. S. Small Business Administration. He wrote the SBA comments on the original ADA legislation and has been active in ADA regulatory work for 15 years. Prior to his work with SBA, Mr. Gray was Deputy Director of the Peace Corps. In addition to his ADA work over the last 15 years, Mr. Gray has also consulted with approximately 30 governments and numerous international agencies (United Nations, OECD, etc.) on improving regulatory practices.
2 Gathering data as a byproduct of operating reports is a standard practice for the U.S. Bureau of the Census. Since the data is developed for operating use rather than statistical use, the data is not biased in any way with respect to what the data says about disability issues.
3 The number of ships in the longitudinal sample varies from time to time due to the expansion of the fleet through addition of new ships as they are built. Some ships were removed from the fleet and sold, moved out of U. S. waters or scrapped. The number of new ships added was greater than the number of ships removed from the sample so the sample fleet grew over the seven years for which data was collected. On average the newer ships were larger and carried more passengers than the ships that were dropped from the sample. The number of passengers carried by the ships in the longitudinal sample increased from approximately two million passengers in the year 2000 to approximately three million passengers in the year 2006.
4 See Chart 3, below for a visual display of usage rates of accessible cabins and nonaccessible cabins by individuals using wheelchairs.
5 This is due to the wider doors and passageways into the cabin and into the bathroom, the larger bathroom required to provide a turning radius for a wheelchair, the wider space next to the bed or between beds, etc.
6 Revenue will fall because no cabin rental income is received. It will fall further because the individuals who would have been in the missing cabin cannot purchase or use other ship services.
7 The number of accessible cabins for each ship was provided by the respective cruise line, using its own definition of what constitutes an accessible cabin. Their definitions may not be congruent with each other or with the specifications for accessible cabins contained in the draft Passenger Vessel Accessibility Guidelines.
8 Some ships may sail from one port throughout the year, while others may have different itineraries from different ports depending on the season of the year and the demand for a particular itinerary Some ships may alternate three or four day trips while others sail on a weekly schedule on six or sevenday trips. The luxury cruise lines may feature longer trips and constantly changing itineraries.
9 The number of passengers at full capacity is generally measured as two persons per cabin (filling the two lower berths in the cabin. Some cabins can be outfitted with additional beds and a number of cabins may be occupied by more than two people. Total occupancy may then be greater than the stated capacity on the ship.
10 The fractional nature of the average number of wheelchairs (also called the mean number or the arithmetical mean) reflects the fact that the mean or average value is determined by summing the number of wheelchair users for all voyages and then dividing by the number of voyages.
11 Both the mean and the standard deviation are shown with only one decimal point. This is done for ease of exposition.
12 Since 1.96 is very close to two, two was actually used as the multiplier. If we use 1.96 then the 95% confidence interval is from 0.84 to 14.56.
13 The reader may note that the number 1.96 times the standard deviation is used to define the upper and lower limits of the confidence level, while at other times the number 2 times the standard deviation is used in the same manner. The numbers are close enough that they define essentially the same confidence level.
14 This section stresses that a certain proportion of passengers come on board using a wheelchair. Some of these individuals may use a wheelchair only incidentally for longer distances onboard or in port. If this is true, then the person using a wheelchair may not request an accessible cabin.
15 The number of accessible cabins requested may vary from voyage to voyage. If only eight accessible cabins were available, some people wanting accessible cabins might not have been able to travel on a particular voyage. It is also true, however, that some passengers without disabilities also might not have been able to travel on a particular voyage where nonaccessible cabins are sold out.
16 Just as the number of wheelchair users rises in the latter half of the year, the total passenger count also rises. The ratio between number of wheelchair users and number of passengers doesn’t increase as much as it would if only the number of wheelchairs was increasing.
17 Keep in mind that even when the proportion of individuals using wheelchairs is growing relative to the general population, the size of the cruise fleet and the availability of accessible cabins may be increasing even more rapidly as the general demand for cruising increases.
18 In doing this, the assumption is that the ratio of wheelchair users in accessible cabins to wheelchair users in nonaccessible cabins does not change from yeartoyear. The sample does show that the ratio varies between cruise lines in 2005, but it does not vary by a large percentage, and it appears reasonable to assume that the ratio does not vary much over time.
19 Again, this may be reflective of the fact that individuals using wheelchairs during a cruise include not only those who use chairs fulltime, but also those who use chairs only incidentally (such as for distance) and therefore may not need or want an accessible cabin.
20 Need for accessible cabins on some voyages may certainly exceed the number of accessible cabins available—but need for nonaccessible cabins may also exceed the number of nonaccessible cabins on a given voyage. Both passengers with and without disabilities may have to change their vacation plans.
21 Obviously, it is not possible to have 12.43 wheelchair users onboard. Voyages with 13, 14, 15, or 16 wheelchair users onboard would be counted in this category.
22 Note that there is no detail shown for two or more standard deviations below the mean. This is because very small numbers of wheelchair users on a given cruise would not pose a problem related to the number of accessible cabins.
23 All of the numbers here indicate that the distribution in usage of wheelchairs on cruise ships follows what statisticians call a normal distribution.
24 For the whole 2005 sample, the ratio of wheelchairs in nonaccessible cabins to wheelchairs in accessible cabins was 70 percent to 30 percent. This ratio can also be expected to vary across voyages and across cruise lines depending on such things as average per day cost per cabin, length of voyage, itinerary, etc. We did observe some variance in this ratio between cruise lines, but the proportion of wheelchair users choosing accessible cabins was no higher than 40 percent on any cruise line.
25 This will vary from line to line depending on its pricing relative to competing lines. The average daily income per cabin was prepared by CLIA using reports from member cruise lines.
26 Nothing has been said yet about the costs of installing accessible cabins relative to the revenue loss resulting from the loss of nonaccessible cabins. In the long run, the revenue losses from cabins which disappear will be much greater than the installation costs for accessible cabins. This study does not address the cost of fabricating accessible cabins; however, that cost is a onetime cost as compared to the ongoing nature of the revenue losses over the life of the ship.
27 A ship operating on Lake Superior might visit a Canadian port but no attempt was made to identify the extent of this activity. Other ships make coastal calls from one American port to another but do not visit any foreign ports and these ships are excluded from the estimate. One exception to this rule are the ships cruising in the Hawaiian Islands. These ships may visit only Hawaiian ports or they may sometimes include a foreign destination to islands outside the state of Hawaii.
28 The number of cabins is lower than the number published by CLIA by approximately 20,000 cabins because some ships operating outside of the United States have been dropped from the estimates used here.
29 Wait staff and cabin stewards may decrease slightly in numbers but most of the staff will remain unchanged.
30 Other major costs, including financing costs, will remain the same when revenue falls. If profits are a lower percentage of total revenue, this likely will negatively impact the industry’s ability to finance continued growth of the fleet.
31 This number includes both cabin rental income plus miscellaneous expenditures on other goods and services purchased on board.
32 This does not necessarily mean that the number of ships in the fleet increases by an average of three percent per year. In recent years the size of new ships has been increasing as has the number of cabins per ship. This trend may be expected to continue into the future. The revenue increase per year may vary over time depending on the growth in desire for cruising each year and on the economic state of the world in a given year. Is this saying that the whole thing is not statistically valid? Just what is the point here. See my comment #46.
33 On modern ships, standard cabin modules are built on shore using modern production line technology to minimize the cost of production. Accessible cabins, on the other hand are usually built on board ship, by hand, at much greater expense per cabin.