Between 1990 and 2000 there are large increases in the population of people with
disabilities as related to transportation. The questions asked on the long form changed
substantially and the data is presented differently. In 1990, the data was presented as
people who have either mobility or self-care disabilities (I suppose you chose one or
both). In 2000, I believe the question was formatted to ask if people had disabilities
that affected their ability to travel outside the home. The data is presented by type of
disability including Sensory, Physical, Mental, Self-Care, Go-Outside-Home, and Employment
disabilities.
I am wondering if anyone knows how much of the increase in the number of people reporting
"Go-Outside-Home Disabilities" over the 1990 "Mobility Limitations" is
due to the way in which the questions were asked and how much is due to increases in this
population? The elderly have a higher incidence of disabilities so as the elderly
population increases one would expect an increase in the numbers of people with
"Mobility" or "Go-Outside-Home" disabilities. Also, the incidence of
certain kinds of disabilities has been increasing in new-borns.
In the past I have used formulas to calculate transit demand for the general population or
for the population of the elderly and disabled. They are calibrated based on the 1990
definitions. When I use the 2000 numbers, there are some definite problems - the formula
for Elderly and Disabled trip demand is higher than the Total trip demand. How might I
need to adjust these to account for differences in the definitions? Has anyone worked on
adjusting or re-calibrating demand formulas based on the new definitions and actual
ridership in communities?
Suzanne O'Neill
TransitPlus, Inc.
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