=+n 1 and varT4 2mn 1m n 1 n 1 2 n 2 (Hackl and Katzenbeisser, 1984) The

=+n þ 1 and varðT4Þ ¼ 2mðn  1Þðm þ n þ 1Þ

ðn þ 1Þ

2

ðn þ 2Þ

(Hackl and Katzenbeisser, 1984)

The statistics T3 and T4 have been proposed as tests for H0:FX ¼ FY against the alternative that the dispersion of FX exceeds the dispersion of FY.