[R-sig-ME] same model runs in nlme but not lme4

[Ben Bolker]

   Because lme4 is fussier than lme.  lme will fit models where the 
variance components are jointly unidentifiable; lmer tries to detect 
these problems and complains about them.  It's possible that this is a 
false positive.  You can make it run by specifying

m1 <- lmer(y~ group*year + (year|stid), data = dat, 
control=lmerControl(check.nobs.vs.nRE="ignore"))

   but I strongly recommend that you think about whether this might be 
exposing problems.

  calculating the profile suggests a little bit of weirdness.

pp <- profile(m1,signames=FALSE)

dd <- as.data.frame(pp)

library(ggplot2)
ggplot(dd,aes(.focal,.zeta)) + geom_point() + geom_line() + 
facet_wrap(~.par,scale="free_x")

You can compare confint(pp) to intervals(m2); they're mostly consistent, 
but some caution is suggested for the CIs on the correlation and the year SD


On 5/22/20 5:57 PM, Simon Harmel wrote:
> Hi All,
>
> I was wondering why my model runs ok when I use `nlme` package but it fails
> when I use the `lme4` package, am I missing something?
>
> Thanks, Simon
>
> #===================================
> library(lme4)
> library(nlme)
>
> dat <- read.csv('https://raw.githubusercontent.com/hkil/m/master/z.csv')
>
> m1 <- lmer(y~ group*year + (year|stid), data = dat)       ## Fails ###
>
> m2 <- lme(y~ group*year, random = ~year|stid, data = dat) ## Runs ###
>
> 	[[alternative HTML version deleted]]
>
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