[R] changing degrees of freedom in summary.lm()

[Spencer Graves]

	  I believe your difficulties will be greatly enlightened by using 
either lme in library(nlme) or lmer associated with the lme4 package. 
Essential documentation is Pinheiro and Bates (2000) Mixed-Effects 
Models in S and S-Plus (Springer).

	  hope this helps.
	  spencer graves

Joseph LeBouton wrote:
> Hello all,
> 
> I'm trying to do a nested linear model with a dataset that incorporates 
> an observation for each of several classes within each of several plots. 
>   I have 219 plots, and 17 classes within each plot.
> 
> data.frame has columns "plot","class","age","dep.var"
> 
> With lm(dep.var~class*age),
> 
> The summary(lm) function returns t-test and F-test values evaluated as 
> though I were working with 219*17-17=3706 degrees of freedom, when in 
> fact I have but 219-17=202 df.  I'm probably being dense on this one, 
> but is there a way I can set df to the proper number so that summary.lm 
> does the correct significance test?  Or should I be doing an entirely 
> different anlaysis?
> 
> Thanks,
> 
> -jlb