allbacks R Documentation

## Measurements on a Selection of Books

### Description

The `allbacks` data frame gives measurements on the volume and weight of 15 books, some of which are softback (pb) and some of which are hardback (hb). Area of the hardback covers is also included.

### Usage

`allbacks`

### Format

This data frame contains the following columns:

volume

book volumes in cubic centimeters

area

hard board cover areas in square centimeters

weight

book weights in grams

cover

a factor with levels `hb` hardback, `pb` paperback

### Source

The bookshelf of J. H. Maindonald.

### Examples

```print("Multiple Regression - Example 6.1")
attach(allbacks)
volume.split <- split(volume, cover)
weight.split <- split(weight, cover)
plot(weight.split\$hb ~ volume.split\$hb, pch=16, xlim=range(volume), ylim=range(weight),
ylab="Weight (g)", xlab="Volume (cc)")
points(weight.split\$pb ~ volume.split\$pb, pch=16, col=2)
pause()

allbacks.lm <- lm(weight ~ volume+area)
summary(allbacks.lm)
detach(allbacks)
pause()

anova(allbacks.lm)
pause()

model.matrix(allbacks.lm)
pause()

print("Example 6.1.1")
allbacks.lm0 <- lm(weight ~ -1+volume+area, data=allbacks)
summary(allbacks.lm0)
pause()

print("Example 6.1.2")
oldpar <- par(mfrow=c(2,2))
plot(allbacks.lm0)
par(oldpar)
allbacks.lm13 <- lm(weight ~ -1+volume+area, data=allbacks[-13,])
summary(allbacks.lm13)
pause()

print("Example 6.1.3")
round(coef(allbacks.lm0),2)  # Baseline for changes
round(lm.influence(allbacks.lm0)\$coef,2)
```