4. Consider the setting and data of Exercise 3. (a) Use hand calculations to conduct the Kruskal-Wallis test at level = 0.05, stating any

4. Consider the setting and data of Exercise 3.

(a) Use hand calculations to conduct the Kruskal-Wallis test at level α = 0.05, stating any assumptions needed for its validity. (Hint. There are no ties in this data set. You may use attach(sl); ranks=rank(values);

rms=by(ranks, ind, mean) to compute the rank averages.)

(b) Use the R command kruskal.test(sl$values∼sl$ind) to conduct the Kruskal-Wallis test. Report the value of the test statistic, the p-value, and whether or not the null hypothesis is rejected at level α = 0.05.