代码如下：
dataExamfedulevel<−as.factor(dataExamfedulevel<−as.factor(dataExam_fedu_level)
dataExamyear<−as.factor(dataExamyear<−as.factor(dataExam_year)
dataExamyear<−relevel(dataExamyear<−relevel(dataExam_year,ref="2016")
dataExamfbmi<−as.factor(dataExamfbmi<−as.factor(dataExam_fbmi)
dataExamfjob<−as.factor(dataExamfjob<−as.factor(dataExam_fjob)
MEE.Age<-function(data)
  require(mfx)
  require(Hmisc)
  require(margins)
  dataExamfbmi<−droplevels(impute(dataExamfbmi<−droplevels(impute(dataExam_fbmi,median))
  dataExamfjob<−droplevels(impute(dataExamfjob<−droplevels(impute(dataExam_fjob,median))
  dataExamfedulevel<−droplevels(impute(dataExamfedulevel<−droplevels(impute(dataExam_fedu_level,median))

  for(i in ncol(data):1) if(nlevels(data[,i])==1) data<-data[,-i]

  age.glm<-glm(formula=paste("Exam_fage~Exam_year+",paste(names(data)[3:ncol(data)],collapse="+"),sep=""),family=gaussian(),data=data)
出现错误：Error in `contrasts<-`(`*tmp*`, value = contr.funs[1 + isOF[nn]]) :
有偿求解决方法