Analgesics. A pharmaceutical company tested three formulations of a pain relief medicine for migraine headache sufferers. For the experiment, 27 volunteers were selected and 9 were randomly assigned to one of three drug formulations. The subjects were instructed to take the drug during their next migraine headache episode and to report their pain on a scale of 1 no pain to 10 extreme pain, 30 minutes after taking the drug.

a) Use the Kruskal-Wallace test to judge whether there is a difference among the analgesics.

b) What aspect of these data may make the Kruskal-Wallace test more appropriate for these data than the ANOVA methods of Chapter 21?

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