Data for Exercise 7.55

Coffee

Format

A data frame/tibble with nine observations on three variables

without

workers' productivity scores without a coffee break

with

workers' productivity scores with a coffee break

differences

with minus without

References

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

Examples


qqnorm(Coffee$differences)
qqline(Coffee$differences)

shapiro.test(Coffee$differences)
#> 
#> 	Shapiro-Wilk normality test
#> 
#> data:  Coffee$differences
#> W = 0.89448, p-value = 0.2217
#> 
t.test(Coffee$with, Coffee$without, paired = TRUE, alternative = "greater")
#> 
#> 	Paired t-test
#> 
#> data:  Coffee$with and Coffee$without
#> t = 1.1767, df = 8, p-value = 0.1366
#> alternative hypothesis: true difference in means is greater than 0
#> 95 percent confidence interval:
#>  -0.580312       Inf
#> sample estimates:
#> mean of the differences 
#>                       1 
#> 
wilcox.test(Coffee$with, Coffee$without, paired = TRUE, 
alterantive = "greater")
#> Warning: cannot compute exact p-value with ties
#> Warning: cannot compute exact p-value with zeroes
#> 
#> 	Wilcoxon signed rank test with continuity correction
#> 
#> data:  Coffee$with and Coffee$without
#> V = 25.5, p-value = 0.324
#> alternative hypothesis: true location shift is not equal to 0
#>