Compressive strength of concrete blocks made by two different methods

Data for Example 7.17

Concrete

Format

A data frame/tibble with 20 observations on two variables

strength

comprehensive strength (in pounds per square inch)

method

factor with levels new and old indicating the method used to construct a concrete block

References

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

Examples

wilcox.test(strength ~ method, data = Concrete, alternative = "greater")
#> Warning: cannot compute exact p-value with ties
#> 
#> 	Wilcoxon rank sum test with continuity correction
#> 
#> data:  strength by method
#> W = 81, p-value = 0.0104
#> alternative hypothesis: true location shift is greater than 0
#>