*! version 1.0.0. 1 Jan 1997 STB-36 sg69
program define mwstati
    version 4.0
    mac def S_8    /* will be mann-whitney statistic */
    local options "pp PRoportion Matched-t Independent-t"
    parse "`*'", parse(" ,")
    confirm number `1'
    confirm number `2'
    if "`5'" != "" & "`4'" != "," {
         di in red "cannot use two options at once"
         exit 198
    }
    if "`3'" == "," {
         if "`4'" == "pp" { local opt = "pp" }
         if substr("`4'",1,2) == "pr" { local opt = "pr" }
         if substr("`4'",1,1) == "m" { local opt = "mt" }
    }
    if "`5'" != "" { local opt = "it" }
    if "`5'" != "" { confirm number `3' }
    if "`opt'" == "pp" {
         local mwstat = `1' / `2'
    }
    if "`opt'" == "pr" {
         local mwstat = .5 + .5 * (`1' - `2')
    }
    if "`opt'" == "mt" {
         local mwstat = normprob(`1' / `2')
    }
    if "`opt'" == "it" {
         local mwstat = normprob(`1' / sqrt(`2' + `3'))
    }
    di "Mann-Whitney statistic for this situation is: " %5.4f `mwstat'
    global S_8 = `mwstat'
end