Data for Exercise 10.14

`Board`

A data frame/tibble with 7 observations on three variables

- salary
1999 salary (in $1000) for board directors

- university
a factor with levels

`A`

,`B`

, and`C`

Kitchens, L. J. (2003) *Basic Statistics and Data Analysis*.
Pacific Grove, CA: Brooks/Cole, a division of Thomson Learning.

```
boxplot(salary ~ university, data = Board, col = c("red", "blue", "green"),
ylab = "Income")
tapply(Board$salary, Board$university, summary)
#> $A
#> Min. 1st Qu. Median Mean 3rd Qu. Max.
#> 60.0 77.5 90.0 133.6 160.0 310.0
#>
#> $B
#> Min. 1st Qu. Median Mean 3rd Qu. Max.
#> 30.0 62.5 80.0 107.9 135.0 250.0
#>
#> $C
#> Min. 1st Qu. Median Mean 3rd Qu. Max.
#> 60.0 95.0 260.0 415.7 600.0 1200.0
#>
anova(lm(salary ~ university, data = Board))
#> Analysis of Variance Table
#>
#> Response: salary
#> Df Sum Sq Mean Sq F value Pr(>F)
#> university 2 408431 204215 2.815 0.08635 .
#> Residuals 18 1305800 72544
#> ---
#> Signif. codes: 0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1
if (FALSE) {
library(dplyr)
dplyr::group_by(Board, university) %>%
summarize(Average = mean(salary))
}
```