"Chris Bergstresser" <[EMAIL PROTECTED]> writes: > On 3/30/06, Prof Brian Ripley <[EMAIL PROTECTED]> wrote: > > I think you want print or summary rather than anova. anova() is not very > > useful for aov() models even without error strata. > > That's sort of better. summary(aov(time ~ drink + Error(video), > data = df)); > > gives me: > > Error: video > Df Sum Sq Mean Sq F value Pr(>F) > Residuals 2 160 80 > > Error: Within > Df Sum Sq Mean Sq F value Pr(>F) > drink 1 240.000 240.000 44.211 1.313e-08 *** > Residuals 56 304.000 5.429 > --- > Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1 > > ...what I'm really looking for is something akin to the output from > SAS, which is: > > Source DF Anova SS Mean Square F Value Pr > F > DRINK 1 240.000 240.000 12.00 0.0742 > VIDEO 2 160.000 80.000 4.00 0.2000 > > > I didn't follow how the videos were chosen. Random effects apply when the > > 'treatments' were chosen from a large population (which might apply if > > each subject watched (on separate occasions) three videos chosen randomly > > from a larger pool), and if the interest is in the variability of the > > response over videos in the pool. If subjects were observed more than > > once then I suspect you most likely want a random effect for subjects. > > This problem comes directly from the final for my Experimental > Stats class, which is why it feels a little odd. The videos were > randomly selected from a library. Subjects watched one of the three > videos, drank one of the two drinks, and completed the tasks. There > were no repeated measures, so we can't block on subjects. > The hypothesis test, according to SAS, treats DRINK*VIDEO as an > error term. Setting aside whether this is the right analysis, how can > I replicate this analysis in R?
Possibly, time ~ drink + Error(video/drink) It won't give you the F test for "video" though. Not quite sure whether time ~ drink + video + Error(video:drink) works. It might, although it is a bit unnatural to have a random interaction between to systematic effects. -- O__ ---- Peter Dalgaard Ă˜ster Farimagsgade 5, Entr.B c/ /'_ --- Dept. of Biostatistics PO Box 2099, 1014 Cph. K (*) \(*) -- University of Copenhagen Denmark Ph: (+45) 35327918 ~~~~~~~~~~ - ([EMAIL PROTECTED]) FAX: (+45) 35327907 ______________________________________________ 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