Data simulation was used to investigate whether tests performed on aligned ranks (Beasley, 2002) could be used as robust alternatives to parametric methods for testing a split-plot interaction with non-normal data and heterogeneous covariance matrices. Results indicated the aligned rank method do not have any distinct advantage over parametric methods in this situation.
Lei, Xiaosheng; Holt, Janet K.; and Beasley, T. Mark
"Aligned Rank Tests As Robust Alternatives For Testing Interactions In Multiple Group Repeated Measures Designs With Heterogeneous Covariances,"
Journal of Modern Applied Statistical Methods: Vol. 3
, Article 17.
Available at: http://digitalcommons.wayne.edu/jmasm/vol3/iss2/17