Hello, I've got what I'd expect to be a pretty simple issue: I fit an aov object using multiple error strata, and would like some significance tests for the contrasts I specified.
In this contrived example, I model some test score as the interaction of a subject's gender and two emotion variables (angry, happy, neutral), measured at entry to the experiment (entry) and later manipulated (manip). This is a fully within-subjects design. Polynomial contrasts examine the effect of increasing emotional state levels(entry) and (manip) are "a" "n" "h", so I set contrasts(entry) <- contrasts(manip) <- contr.poly(3) (I am led to believe that this is equivalent to specifying contrasts=list(entry=contr.poly(3), manip=contr.poly(3)) in the aov call) ...and then fit the model: fit <- aov(score ~ gender*entry*manip + Error(subject/(entry*manip)) ...at this point, summary(fit) tests all the main effects and interactions I'm interested in, and coef(fit) has the coefficients for all the contrasts and their interactions. The question, however, is how to test the significance of the contrasts, which is to say, compute the standard errors and apply them to coef(fit) in a meaningful way. The se.contrasts() function looks quite appealing, though it appears to require me to respecify the contrasts...in both a contrast.obj and a coef. It is not at all clear from the instrutions what contrast.obj is, especially given that I have already specified the contrasts and they are already represented in coef(fit). I may be missing something here. Could someone suggest a way to go from coef(fit) to a table like summary(fit) which tests the single-df contrasts (and interactions therebetween) which I specified? Or a way to compute the standard errors for these contrasts? Many thanks, Adam Kramer ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
