The documentation for `ASECWT`

says:

ASECWT is based on the inverse probability of selection into the sample and adjustments for the following factors: failure to obtain an interview; sampling within large sample units; the known distribution of the entire population according to age, sex, and race; over-sampling Hispanic persons;

to give husbands and wives the same weight; and an additional step to provide consistency with labor force estimates from the basic survey.

However I find that for some observations, `ASECWT`

is not equal to `ASECWT_SP`

. Granted, those are very few cases corresponding to 0.01% of my data. Is there more documentation on how those weights are constructed?