Data for Exercise 7.60

German

## Format

A data frame/tibble with ten observations on three variables

student

a character variable indicating student number

when

a character variable with values Before and After to indicate when the student received experimental instruction in German

errors

the number of errors in copying a German passage

## Examples


t.test(errors ~ when, data = German, paired = TRUE)
#>
#> 	Paired t-test
#>
#> data:  errors by when
#> t = -3.638, df = 9, p-value = 0.005417
#> alternative hypothesis: true difference in means is not equal to 0
#> 95 percent confidence interval:
#>  -4.0545188 -0.9454812
#> sample estimates:
#> mean of the differences
#>                    -2.5
#>
wilcox.test(errors ~ when, data = German)
#> Warning: cannot compute exact p-value with ties
#>
#> 	Wilcoxon rank sum test with continuity correction
#>
#> data:  errors by when
#> W = 26, p-value = 0.0739
#> alternative hypothesis: true location shift is not equal to 0
#>

if (FALSE) {
T8 <- tidyr::spread(German, when, errors) %>%
mutate(di = After - Before, adi = abs(di), rk = rank(adi), srk = sign(di)*rk)
T8
qqnorm(T8$di) qqline(T8$di)
t.test(T8\$srk)
}