AvgDailyGain {SASmixed}R Documentation

Average daily weight gain of steers on different diets

Description

The AvgDailyGain data frame has 32 rows and 6 columns.

Format

This data frame contains the following columns:

Id
the animal number
Block
an ordered factor indicating the barn in which the steer was housed.
Treatment
an ordered factor with levels 0 < 10 < 20 < 30 indicating the amount of medicated feed additive added to the base ration.
adg
a numeric vector of average daily weight gains over a period of 160 days.
InitWt
a numeric vector giving the initial weight of the animal
Trt
the Treatment as a numeric variable

Source

Littel, R. C., Milliken, G. A., Stroup, W. W., and Wolfinger, R. D. (1996), SAS System for Mixed Models, SAS Institute (Data Set 5.3).

Examples

options(contrasts = c(unordered = "contr.SAS", ordered = "contr.poly"))
if (require("lattice", quietly = TRUE, character = TRUE)) {
  ## plot of adg versus Treatment by Block
  xyplot(adg ~ Treatment | Block, AvgDailyGain, type = c("g", "p", "r"),
         xlab = "Treatment (amount of feed additive)",
         ylab = "Average daily weight gain (lb.)", aspect = "xy",
         index.cond = function(x, y) coef(lm(y ~ x))[1])
}
# compare with output 5.1, p. 178
(fm1Adg <- lmer(adg ~ InitWt * Treatment - 1 + (1 | Block), AvgDailyGain))
anova(fm1Adg)   # checking significance of terms
(fm2Adg <- lmer(adg ~ InitWt + Treatment + (1 | Block), AvgDailyGain))
anova(fm2Adg)
summary(lmer(adg ~ InitWt + Treatment - 1 + (1 | Block), AvgDailyGain))

[Package SASmixed version 0.3-4 Index]