chickwts <-
data.frame(weight = c(179, 160, 136, 227, 217, 168, 108, 124, 143,
140, 309, 229, 181, 141, 260, 203, 148, 169, 213, 257, 244, 271, 243, 230,
248, 327, 329, 250, 193, 271, 316, 267, 199, 171, 158, 248, 423, 340, 392,
339, 341, 226, 320, 295, 334, 322, 297, 318, 325, 257, 303, 315, 380, 153,
263, 242, 206, 344, 258, 368, 390, 379, 260, 404, 318, 352, 359, 216, 222,
283, 332), feed = factor(c(2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 3,
3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 1,
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1), levels=1:6, labels = c("casein",
"horsebean", "linseed", "meatmeal", "soybean", "sunflower")))