Sub CHSTWO(BINS1(), BINS2(), NBINS, KNSTRN, DF, CHSQ, PROB)
    DF = NBINS - 1 - KNSTRN
    CHSQ = 0#
    For J = 1 To NBINS
        If BINS1(J) = 0# And BINS2(J) = 0# Then
          DF = DF - 1#
        Else
          CHSQ = CHSQ + (BINS1(J) - BINS2(J)) ^ 2 / (BINS1(J) + BINS2(J))
        End If
    Next J
    PROB = GAMMQ(0.5 * DF, 0.5 * CHSQ)
End Sub