I selected several variables in order to construct a customized dataset from IPUMS USA and then downloaded it in SPSS. After adding person weight, I ran a simple crosstab between the Cognitive Difficulty and Age variables. I did the same for the Self-Care Difficulty and Age variables. For all other ages, I was able to see the number of Yes, No, and N/A responses. However, for children between the ages of 0 and 4, I saw only N/A responses. Are these two items not asked for children in these age groups? Or does N/A refer to “Not assessed”?
The universe of the variable DIFFREM is persons age 5+ in all samples it is available. The universe of the variable DIFFCARE is persons age 5+ in most samples it is available (it is persons age 15+ in 1990). This means that children age 0-4 not in universe for the survey questions corresponding to these two variables. The universe of each variable, displayed in the universe tab of the variable, defines who the question is asked of or about.
I hope this is helpful. Please follow up with any additional questions.