I have two independent samples from two cities. I want to compare the average money they spend on coffees each month. I am using PROC SURVEYMEANS but I am not sure if I am using the right statement to identify cities.  In this document: http://www.math.wpi.edu/saspdf/stat/chap61.pdf   It says to use stratum to compare two independent samples but I tried it and it did not give me a reasonable result.    My results from using DOMAIN and DIFF look fine when I compare the p-value for the t-statistic and the CI for each mean. However, my concern is if I was comparing the average money spent on coffee for men and women in one sample (instead of two independent samples that I have in my study) I still would use the same DOMAIN and DIFF statements. Does that make sense? Thanks!   proc surveymeans data=&dataset nobs mean stderr var cv clm min max median plots=none; var coffee_spent ; domain cities/diff; weight &weight_var; run; The SURVEYMEANS Procedure Statistics for WAVE Domains cities Variable N Minimum Maximum Mean Std Error of Mean Var of Mean 95% CL for Mean Coeff of Variation 2 coffee_spent 1368 1.4 50.0 12.42 0.3 0.091658 11.83 13.01 0.024 3 coffee_spent 1243 1.7 57.5 13.42 0.4 0.124780 12.72 14.11 0.026 Differences of HERB_US_PP Means for WAVE Domains cities -cities Diff Estimate Std Error DF t Value Pr > |t| 2 3 -0.996823 0.465238 2610 -2.14 0.0322 ... View more