preceded by is about has_specified_input has_specified_output achieves_planned_objective data transformation ANOVA studentized range distribution false positive rate post-hoc analysis study group population expected value between group comparison objective Newman-Keuls test post-hoc analysis 1 2 Orlaith Burke Alejandra Gonzalez-Beltran Philippe Rocca-Serra SNK.test(y, trt, DFerror, MSerror, alpha = 0.05, group=TRUE, main = NULL) http://artax.karlin.mff.cuni.cz/r-help/library/agricolae/html/SNK.test.html The Newman–Keuls or Student–Newman–Keuls (SNK) method is a stepwise multiple comparisons procedure used to identify sample means that are significantly different from each other. It was named after Student (1927), D. Newman, and M. Keuls. This procedure is often used as a post-hoc test whenever a significant difference between three or more sample means has been revealed by an analysis of variance (ANOVA). The Newman–Keuls method is similar to Tukey's range test as both procedures use Studentized range statistics.Compared to Tukey's range test, the Newman–Keuls method is more powerful but less conservative. adapted from wikipedia: last accessed: 2013-11-15 p-value ready for release