Apple Hardness

An experiment was undertaken where seventeen recently picked (Fresh) apples were randomly selected and measured for hardness. Seventeen apples were also randomly selected from a warehouse (Warehouse) where the apples had been stored for one week. Data are used in Example 8.10.

Format

A data frame with 17 observations on the following 2 variables: #'

• Fresh (hardness rating measured in \(\texttt{kg}/\texttt{meter}^2\))

• Warehouse (hardness rating measured in \(\texttt{kg}/\texttt{meter}^2\))

Source

Ugarte, M. D., Militino, A. F., and Arnholt, A. T. (2008) Probability and Statistics with R. Chapman & Hall/CRC.

Examples

# Figure 8.5
attach(Apple)
par(pty = "s")
Altblue <- "#A9E2FF"
Adkblue <- "#0080FF"
fresh <- qqnorm(Fresh)
old <- qqnorm(Warehouse)
plot(fresh, type = "n",ylab = "Sample Quantiles", xlab = "Theoretical Quantiles")
qqline(Fresh, col = Altblue)
qqline(Warehouse, col = Adkblue)
points(fresh, col = Altblue, pch = 16, cex = 1.2)
points(old, col = Adkblue, pch = 17)
legend(-1.75, 9.45, c("Fresh", "Warehouse"), col = c(Altblue, Adkblue),
text.col = c("black","black"), pch = c(16, 17), lty = c(1, 1), bg = "gray95", cex = 0.75)
title("Q-Q Normal Plots")
detach(Apple)
# Trellis approach
qqmath(~c(Fresh, Warehouse), type = c("p","r"), pch = c(16, 17),
cex = 1.2, col=c("#A9E2FF", "#0080FF"),
groups=rep(c("Fresh", "Warehouse"), c(length(Fresh), length(Warehouse))),
data = Apple, ylab = "Sample Quantiles", xlab = "Theoretical Quantiles")