Analysis Plan Regional Meeting of UN Washington City Group on Disability Statistics Rio de Janeiro, Brazil September 19-20
Objective • To test the consistency of the Washington Group (WG) census questions in regards to how their interpretation may differ by: • Different core domains • Countries • Subpopulations
For ease of analysis we need binary variables To not lose richness of responses, we can used different definitions D1=1 if some difficulty, a lot, or can’t do at all D2=1 if a lot of difficulty or can’t do at all D3=1 if can’t do at all Step 1: Construct Different Measures of Disability
Step 2: Compute Disability Prevalence • Prevalence measured four ways: • P1=1 if at least one domain has D1=1 • P2=1 if at least one domain has D2=1 • P3=1 if at least one domain has D3=1 • PM=1 if more than one domain has D1=2 • These prevalence rates can be compared with measures from previous country instruments to get a sense of what they are measuring relative to the WG questions
Step 3: Construct Extended Measures • Extended measures get at a deeper sense of how people are answering the core questions • For example, for vision: • Core question:Do you have difficulty seeing, even if wearing glasses? • Extended questions: A) Do you have difficulty seeing and recognizing a person across the road? B) Do you have difficulty seeing and recognizing an object at arm’s length?
Question Order • In order not to “contaminate” the results of the WG questions, it is important that all six core questions be asked prior to the extended questions
Constructing Extended Measures • Within each domain… • ED1 = 1 if at least one extended question in that domain has a response of some difficulty, a lot of difficulty, or can’t do at all • ED2 = 1 if at least one extended question in that domain has a response of a lot of difficulty or can’t do at all • ED3 = 1 if at least one extended question in that domain has a response of can’t do at all
Step 4: Correlation analysis • When people are answering the core questions, how does that relate to the underlying concepts in the extended questions? • It could be that people respond positively to one set or questions but not the other, so define • D0 = 1 if there are no reported difficulties • ED0 =1 if there are no reported difficulties in any of the extended questions
How do core and extended questions relate? • Using correlation coefficients test if there are statistically significant differences between the D and ED measures • D0 vs. ED0, D1 vs. ED1, etc. • If they differ, then the measures are not equivalent • If they aren’t equivalent, does one set identify more people as disabled?
Step 5: Differences by Subpopulation • Older people • Gender • Rural vs. Urban • Ability to examine subpopulations depends on sample size.