>Why not...
>
>

>use trial
>go top
>scan
>do case
>    case trial.min_sex = 'F'
>        replace min_f with .t.
>        replace min_m with .f.
>
>    case trial.min_sex = 'M'
>        replace min_f with .t.
>        replace min_m = .f.
>endcase
>endscan
>

even better...

repl all min_f with .T. for min_sex = 'F'
repl all min_m with .T. for min_sex = 'M'