I’m trying to use the variables “DIFFMOB” (independent living difficulty) and “DIFFCARE” (self-care difficulty) in 1990, 2000 and 2006/2007 ACS. From what I can tell the questionnaire text is pretty similar in these surveys. However, the 2000 numbers appear to be outliers for both of these variables.
The number of people with independent living difficulty goes from ~10M in 1990, to almost 20M in 2000, and then back down to 14M in 2006. The number of people with a self-care difficulty goes from 10M in 1990 down to 7.6M in 2000 before returning to 9M in 2006/2007. Does anyone know if there’s something about the 2000 census that I’m missing regarding these variables?
The DIFFMOB comparability tab emphasizes a difference between the 2002 and 2003 disability estimates; however, the report it links to provides a bit more context and explicitly calls out potential issues with the counts in the 2000 data that are present in the 2001 and 2002 ACS data as well:
Evidence presented at the 2003 Joint Statistical Meetings suggested that Census 2000 and the ACS in 2000 included a confusing skip pattern and item wording resulting in over-reporting, specifically in the last two parts of the disability questions…Since the ACS continued to use the same disability items in 2001 and 2002, it seemed likely that the trend of over-reporting continued in those years.
The last two parts of the disability question correspond to the independent living and self-care difficulty questions.