[Gretl-users] Mean compare

Hi, first sorry for the stupid question. I am performing datamining with R from one year and recently found Gretl program. It is wonderful for fast descriptive analysis, mean compare and graphics for novices! Can You tell me what type analysis is calculated from "statistic calculator" when checkbox "assume common population standard population" is not tick? The reason for asking is different "p" results, compared to R, when there is no thick. Thank You in advice for fast answer. dr Iliev