Calculating mean in SAS

To calculate mean simply use proc means

proc means data = work.test;
var ratings;
run;

This will give mean of ratings only.

Mean of sorted data.

proc means data = work.test;
var ratings;
by post;
run;

Above code throws error because data is not sorted. To use by sorting is required.

Thus, sorting data:

proc sort data=work.test;
by post;
run;

Printing only mean

proc means data = work.test mean;
var rating;
class post;
run;

Printing mean max min std

proc means data = work.test mean min max std;
var rating;
class post;
run;

Printing mean min max std meadian sum

proc means data = work.test mean min max std median sum;
var rating;
class post;
run;