@gauravv0103 wrote:   Just wanted to understand what do we mean regarding levels over here, It is a generic numeric variable we are getting the solution we when we run it through either excel data analysis or use Minitab. Then why it is not possible with Proc ttest. Numeric variables are almost never placed in CLASS statements in PROC TTEST. The CLASS statement should contain the name of a category variable that contains two levels. "Generic numeric" variables probably ought to go in the VAR statement. ... View more