linear mixed model using lmer
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 -------------- next part -------------- An embedded and charset-unspecified text was scrubbed... Name: datx.txt URL: <https://stat.ethz.ch/pipermail/r-help/attachments/20220305/296d04e5/attachment.txt>