I am running a means on weighted data in both SAS and Stata and getting wildly different values for standard deviation. The statistician here believes SAS is incorrect. I took the class dataset from sashelp and created two fake weights. t_wt gives everyone a weight of 1 and t_wt2 gives everyone a weight of 5. When running means using each weight I had expected the standard deviation to remain the same as there is no variance in the means or data distribution. (and in Stata, the standard deviation does remain the same). However I am getting a shift in stddev from 22.77 to 50.92 for the weight variable and 5.12 to 11.46 for the height variable. We are having problems explaining why the results are different in SAS and Stata. Any thoughts? data temp2; set sashelp.class; t_wt = 1; t_wt2 = 5; run; proc means data = temp2 mean min max std n std; var weight height; weight t_wt; run; proc means data = temp2 mean min max std n std; var weight height; weight t_wt2; run;
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