Dear list members: I am trying to calculate power for an ANCOVA analysis. I have found different solutions such as power.t.test and power.anova.test but they seem to refer to the ANOVA part of the ANCOVA. My model is of the form: lm (y ~ factor + x1 + x2 + x2*myfactor) where myfactor is a factorial variable. And I am interested in calculating the power of the significance test, mainly for the interaction term between x2 and the factor. I would appreciate you help Xan. -- View this message in context: http://r.789695.n4.nabble.com/ANCOVA-power-tp4630238.html Sent from the R help mailing list archive at Nabble.com.