[R] linear mixed model using lmer

Jeff Newmiller
2022-03-05T00:56:16Z

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On March 4, 2022 4:41:57 PM PST, array chip via R-help <r-help at
r-project.org> wrote:
>Dear all, I have this simple dataset to measure the yeild of a crop
collected in 2 batches (attached). when I ran a simple inear mixed model using
lmer to estimate within-batch and between-batch variability, the between-batch
variability is 0. The run showed that data is singular. Does anyone know why the
data is singular and what's the reason for 0 variability? is it because the
dataset only has 2 batches?
>>
daty<-read.table("datx.txt",sep='\t',header=T,row.names=NULL)
>> library(lme4)> lmer(yield~1+(1|batch),daty)
>boundary (singular) fit: see ?isSingular
>Linear mixed model fit by REML ['lmerMod']
>Formula: yield ~ 1 + (1 | batch)
>? ?Data: daty
>REML criterion at convergence: 115.6358
>Random effects:
>?Groups? ?Name? ? ? ? Std.Dev.
>?batch? ? (Intercept) 0.000? ?
>?Residual? ? ? ? ? ? ?2.789? ?
>Number of obs: 24, groups:? batch, 2
>Fixed Effects:
>(Intercept)??
>? ? ? 5.788??
>
>Thanks!
>John
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