Sub FTEST(DATA1(), N1, DATA2(), N2, F, PROB)
    Call AVEVAR(DATA1(), N1, AVE1, VAR1)
    Call AVEVAR(DATA2(), N2, AVE2, VAR2)
    If VAR1 > VAR2 Then
        F = VAR1 / VAR2
        DF1 = N1 - 1
        DF2 = N2 - 1
    Else
        F = VAR2 / VAR1
        DF1 = N2 - 1
        DF2 = N1 - 1
    End If
    DUM1 = BETAI(0.5 * DF2, 0.5 * DF1, DF2 / (DF2 + DF1 * F))
    DUM2 = 1# - BETAI(0.5 * DF1, 0.5 * DF2, DF1 / (DF1 + DF2 / F))
    PROB = DUM1 + DUM2
End Sub