为什么模型
init.fit<-lmer(y ~ X-1 +(Z -1|subject))
运行之后一直提示
错误: number of observations (=7072) <= number of random effects (=7072) for term (Z - 1 | subject); the random-effects parameters and the residual variance (or scale parameter) are probably unidentifiable
怎么改正~谢谢
急急~