Re: [R] variance estimates in lme biased?

2003-12-17 Thread Gary Allison
Peter Dalgaard wrote: [snip] Or, try looking at a smaller example where things can be worked out explicitly: One-way ANOVA with random btw.group variation. Say 5 groups and 3 obs per group. If I got this right (please do check!), the estimate of the between-group variance is 1/3 times the differenc

Re: [R] variance estimates in lme biased?

2003-12-17 Thread Peter Dalgaard
Thomas Lumley <[EMAIL PROTECTED]> writes: > On Tue, 16 Dec 2003, Gary Allison wrote: > > > Hi all, > > I didn't get a response to my post of this issue a week ago, so I've > > tried to clarify: > > > > When I use lme to analyze a model of nested random effects, the variance > > estimates of level

Re: [R] variance estimates in lme biased?

2003-12-17 Thread Thomas Lumley
On Tue, 16 Dec 2003, Gary Allison wrote: > Hi all, > I didn't get a response to my post of this issue a week ago, so I've > tried to clarify: > > When I use lme to analyze a model of nested random effects, the variance > estimates of levels higher in the hierarchy appear to have much more > varian

Re: [R] variance estimates in lme biased?

2003-12-17 Thread Gary Allison
Pascal, If every run of my simulation produced results like you saw, I would not be concerned. But a sizable fraction of my simulation runs produce much larger standard deviations in level 1, though level 3's estimates stay small. I've posted the results from 500 runs at: http://david.science

Re: [R] variance estimates in lme biased?

2003-12-17 Thread Pascal A. Niklaus
Running lme on your data set results exactly in what you expect - or do you expect something different? Pascal > L1<-factor(F1f) > L2<-factor(F2f) > L3<-factor(F3f) > lme(value ~ 1,random = ~ 1 | L1/L2/L3) Linear mixed-effects model fit by REML Data: NULL Log-restricted-likelihood: 438.9476 F

[R] variance estimates in lme biased?

2003-12-16 Thread Gary Allison
Hi all, I didn't get a response to my post of this issue a week ago, so I've tried to clarify: When I use lme to analyze a model of nested random effects, the variance estimates of levels higher in the hierarchy appear to have much more variance than they should. In the example below with 4 le