[R-sig-eco] marginal vs sequential results of lme

2011-01-20 Thread Iannone, Basil
Dear R users, I am having a problem with interpreting "anova" results of a linear mixed effects model. The data I am analyzing is from study that was set up as a randomized block design with two factors at two levels. The model is: m1 <- lme(Y~A*B, random = ~1|Block) The design is comple

Re: [R-sig-eco] marginal vs sequential results of lme

2011-01-20 Thread Ben Bolker
On 11-01-20 12:24 PM, Iannone, Basil wrote: > Dear R users, > > I am having a problem with interpreting "anova" results of a linear mixed > effects model. > > The data I am analyzing is from study that was set up as a randomized > block design with two factors at two levels. The model is: > >

Re: [R-sig-eco] marginal vs sequential results of lme

2011-01-20 Thread Phillip Chapman
Basil, I think that the issue is how lme (and R generally) parameterizes factorial models. The "marginal" anova fits each effect after the others. That does not produce what SAS calls type III sums of squares unless the model has no interactions or you use the "sum to zero" parameterization

Re: [R-sig-eco] marginal vs sequential results of lme

2011-01-22 Thread Basil Iannone
Phillip and Ben, Thanks a bunch. I now understand why sequential and marginal results are not the same, although I have to read up a little on the "contrast" that Ben mentioned. Thanks for the clarification. On Thu, Jan 20, 2011 at 12:51 PM, Phillip Chapman < pchap...@stat.colostate.edu> wrote: