Hi,
I am wondering if someone has any insights about why the person weight variable in the 1990 and 2000 5% sample has a value of 0. In theory, the sample weight should not take a value of 0. Any idea why this is the case in the data? Thank you!
This is noted in the comparability tab for PERWT: In 1990-2000, some cases have PERWT values of 0. This is a function of the complex sample design used by the Census Bureau.
You can read more about the details of the sampling designs at the 1990 sampling design page and 2000 sampling design page. I suspect the zero values of PERWT are due to rounding of weights that were less than 1. Here is a passage from the 1990 sample design page:
The weights obtained from the second iteration for stage IV were assigned to the sample person records. However, to avoid complications in rounding for tabulated data, only whole number weights were assigned. For example, if the final weight of the persons in a particular group was 7.25 then 1/4 of the sample persons in this group were randomly assigned a weight of 8, while the remaining 3/4 received a weight of 7.