I am a relatively new user of PUMS data. I use the 2016 1 year estimate PUMS population data, subset it to a dataset include the individual data for a county within the age group of my interest (ffx). Then I need to calculate the population estimate of the county by race, and need to calculate margin of error for the estimate. Since the margin of error depend on the sampling design, I assume the PUMS population survey did a stratified sampling on state, PUMA area, and housing unit, and wrote the following code to get the 90% confidence interval, and then I can calculate the margin of error as the radius of the interval. Could anyone tell me if my understanding to the PUMS sampling design is correct and if the following SAS code is correct? Thank you so much!

**Proc** **surveyfreq** data = ffx;

Table county*Race/CLWT CL ALPHA = **0.1** ;

strata ST PUMA SERIALNO;

weight PWGTP;

**run**;