CMMSE: a nonparametric test for grouping factor levels: an application to cocoa breeding experiments in acidic soils.

Nonparametric tests can often be applied in many important problems, since they hold under more general conditions than parametric tests. In this work we propose a nonparametric test for grouping of factor levels. We apply that test to a cocoa breeding experiment in Ghana, in which twelve cocoa varieties were compared. There were three groups of varieties, two of which have a common ascendant, and we intend to test if this grouping is significant. The cocoa breeding experiment was carried out in four types of soils. All these types of soils are acidic, so resistance to low pH is an important goal of the plant breeding. The obtained results suggest that the grouping is significant for the most acidic soil. [ABSTRACT FROM AUTHOR]