In lm
and glm
models, I use functions coef
and confint
to achieve the goal:
m = lm(resp ~ 0 + var1 + var1:var2) # var1 categorical, var2 continuous
coef(m)
confint(m)
Now I added random effect to the model - used mixed effects models using lmer
function from lme4 package. But then, functions coef
and confint
do not work any more for me!
> mix1 = lmer(resp ~ 0 + var1 + var1:var2 + (1|var3))
# var1, var3 categorical, var2 continuous
> coef(mix1)
Error in coef(mix1) : unable to align random and fixed effects
> confint(mix1)
Error: $ operator not defined for this S4 class
I tried to google and use docs but with no result. Please point me in the right direction.
EDIT: I was also thinking whether this question fits more to https://stats.stackexchange.com/ but I consider it more technical than statistical, so I concluded it fits best here (SO)... what do you think?
There are two new packages, lmerTest and lsmeans, that can calculate 95% confidence limits for lmer
and glmer
output. Maybe you can look into those? And coefplot2, I think can do it too (though as Ben points out below, in a not so sophisticated way, from the standard errors on the Wald statistics, as opposed to Kenward-Roger and/or Satterthwaite df approximations used in lmerTest
and lsmeans
)... Just a shame that there are still no inbuilt plotting facilities in package lsmeans
(as there are in package effects()
, which btw also returns 95% confidence limits on lmer
and glmer
objects but does so by refitting a model without any of the random factors, which is evidently not correct).