# What are various ATUS weights used for?

I know ATUS has WT06 sampling weight (eqivalent to final weight, FNWGT, in the orginal ATUS), which is used to estimate the means of time for some activity or a set of activities, as per ATUS manual published on BLS website. There are also replicate weights, at least in the original ATUS, that are used to calculate standard errors and to construct the confidence intervals. However, I noticed that IPUMS version of ATUS also has a base weight BWT that sums to the population of the country in a given year as indicated in the variable description, yet it doesn't seem to be a fequency or a probability weight, which makes it confusing to understand in what kinds of scenarios it should be used.

So, for example, if I wanted to run an OLS regression with an outcome of time spent on a certain activity Y, but only for residents of certain (but not all) geographic regions, or some other characteristic that defines a subset of the entire sample, what weight should I use, WT06 or BWT? I tried using BWT as [pw=BWT] option in Stata, which yields reasonable results, but I am not entirely sure.

Thank you in advance for clarification. Any examples of usage of each weight would be helpful.