摘要：For randomized block designs, nonparametric treatment comparisons
are usually made using the Friedman test for complete designs, and the Durbin test
for incomplete designs; see, for example, Conover (1998). This permits assessment
of only the mean rankings. Such comparisons are here extended to permit assessments
of bivariate effects such as the linear by linear effect and the quadratic by
linear, or umbrella effect.
