R混合模型(lme4)错误中的单级变量
原文：single level variables in mixed model (lme4) error in R

set.seed(1234) mydata <- data.frame ( individual = factor(1:10), M1a = factor (sample (c(1,2),10, replace = T)), M1b = factor (sample (c(1,2),10, replace = T)), pop = factor (c(rep(1, 5), ...