## Chicken Weights by Feed Type

### Description

An experiment was conducted to measure and compare the effectiveness
of various feed supplements on the growth rate of chickens.

### Usage

chickwts

### Format

A data frame with 71 observations on the following 2 variables.

`weight`

a numeric variable giving the chick weight.

`feed`

a factor giving the feed type.

### Details

Newly hatched chicks were randomly allocated into six groups, and each
group was given a different feed supplement. Their weights in grams
after six weeks are given along with feed types.

### Source

Anonymous (1948)
*Biometrika*, **35**, 214.

### References

McNeil, D. R. (1977)
*Interactive Data Analysis*.
New York: Wiley.

### Examples

require(stats); require(graphics)
boxplot(weight ~ feed, data = chickwts, col = "lightgray",
varwidth = TRUE, notch = TRUE, main = "chickwt data",
ylab = "Weight at six weeks (gm)")
anova(fm1 <- lm(weight ~ feed, data = chickwts))
opar <- par(mfrow = c(2, 2), oma = c(0, 0, 1.1, 0),
mar = c(4.1, 4.1, 2.1, 1.1))
plot(fm1)
par(opar)