To compare the effectiveness of three types of pain relievers, a homogeneous group of 22 students were divided randomly into three groups, and each group took one of three pain relievers for a period of 2 weeks. The average duration of headaches, in minutes, during the two weeks were recorded.
Brand A: 5.3, 4.2, 3.7, 7.2, 6.0, 4.8
Brand B: 6.3, 9.3, 6.5, 7.7, 8.2, 9.5
Brand C: 2.4, 3.1, 3.7, 4.1, 2.5, 105.0, 5.3
For alpha = 0.01, are there differences in the brands?
Hint: Do not discard any data (use all the data).
NOTE: I need only explanations, hypothesis, model, etc. to be written down. The calculation parts needs to be done in SPSS or SAS, and I need SPSS/SAS outputs, codes too.
This problem was solved using the Kruskal-Wallace procedure. The PROC NPAR1WAY procedure in SAS was the tool for the analysis.