[R-sig-ME] PIECEWISE MIXED-EFFECT MODELING
d.rizopoulos at erasmusmc.nl
Sun Mar 6 16:24:41 CET 2011
the '*' operator has a special meaning inside a formula statement --
have a look at function I() if you'd like to use '*' in the standard
way. Try the following (untested):
CD40 <- lme(cd4 ~ I(rt*(rt<25)) + I(rt*(rt>=25)), data = frame1,
random = ~ rt | id, na.action = na.omit)
I hope it helps.
On 3/6/2011 12:33 AM, Federico Bonofiglio wrote:
> Hi Folks,
> I'd really really appreciate if anyone could give me a quick advise for this
> I want to fit a piecewise mixed effect model, but it seems I'm not getting
> around it
> + random= ~rt|id, na.action=na.omit)
> Errore in MEEM(object, conLin, control$niterEM) :
> Singularity in backsolve at level 0, block 1
> Would anyone have a clue of the matter ?
> Huge thanks.
> Federico Bonofiglio
Department of Biostatistics
Erasmus University Medical Center
Address: PO Box 2040, 3000 CA Rotterdam, the Netherlands
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