#Extract the levels
all_levels <- unique(c(as.character(data$StrainA),as.character(dat$StrainB),as.character(data$StrainC),as.character(dat$StrainD)))
#Define factor for the multiple-membership
data$Strain <- factor(1:nrow(data),levels=all_levels)
#First step of analysis in lmer
lmod <- lFormula(y~1+(1|Strain),data=data,control=lmerControl(check.nobs.vs.nlev="ignore",check.nobs.vs.nRE="ignore",check.nobs.vs.rankZ="ignore"))
lmod$reTrms$Ztlist$`1 | Strain`