I have a question about weights in the FSS. I’m looking at basic monthly data for December 2021. Documentation for the variable FSSTATUS indicates that all households should be in universe, but many observations are coded as NIU. When I add up the weights for all observations in universe, the sum is lower than the total number of households (in Spartanburg County and South Carolina, for reference). Predictably, the weights including the NIU observations add up to the correct number.
In brief - why would any households be coded NIU for FSSTATUS? Thanks in advance!
FSSTATUS is only determined for households who completed the Food Security Supplement (FSSUPINT = 1). Adding this additional qualifier to the universe statement should filter out all NIU responses. We will update the documentation to note this qualifier for the universe. The 2022 FSS codebook (pg. 12) provides additional information on non-interviewed supplement households. It notes that 9,858 households who were interviewed for the December 2022 CPS (HHINTYPE = 1) did not complete the supplement. The codebook also describes the criteria used to determine whether a household completed a partial interview.
When I tabulate FSHWTSCALE, the weight for food security scale data, for South Carolina in 2022, I get a total count of 5,106,244 persons and 2,203,295 households; this differs only slightly from official Census estimates and likely is due to the exclusion of people living in institutions and those on active duty in the armed forces from the CPS universe. The estimates for Spartanburg County were also similarly close to published estimates, though there may be a larger margin of error due to the small number of respondents on the county level.