以下是我的一小部分数据:
dat <-structure(list(sex = structure(c(1L, 1L, 1L, 1L, 1L, 1L, 1L,
1L, 1L, 1L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L), .Label = c("male",
"female"), class = "factor"), A = c(1, 2, 0, 2, 1, 2, 2, 0, 2,
0, 1, 2, 2, 0, 0, 2, 0, 0, 0, 2), B = c(0, 0, 0, 0, 0,