Data for Exercise 7.45

Monoxide

Format

A data frame/tibble with ten observations on two variables

company

a vector with values manufacturer and competitor

emission

carbon monoxide emitted

References

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

Examples


boxplot(emission ~ company, data = Monoxide, col = topo.colors(2))

t.test(emission ~ company, data = Monoxide)
#> 
#> 	Welch Two Sample t-test
#> 
#> data:  emission by company
#> t = 2.1187, df = 16.842, p-value = 0.04929
#> alternative hypothesis: true difference in means is not equal to 0
#> 95 percent confidence interval:
#>  0.001326539 0.760895683
#> sample estimates:
#>   mean in group competitor mean in group manufacturer 
#>                   3.370000                   2.988889 
#> 
wilcox.test(emission ~ company, data = Monoxide)
#> Warning: cannot compute exact p-value with ties
#> 
#> 	Wilcoxon rank sum test with continuity correction
#> 
#> data:  emission by company
#> W = 71, p-value = 0.03617
#> alternative hypothesis: true location shift is not equal to 0
#> 
if (FALSE) {
library(ggplot2)
ggplot2::ggplot(data = Monoxide, aes(x = company, y = emission)) + 
           geom_boxplot() + 
           theme_bw()
}