I am trying to understand the results on the kruskal wallis test that are produced in R. The data that I am testing:
Class Branch LA_type Method_type Method_call Branch_type Branch_condition Tested_parameter Goal 12 Smooth public static never called IFNE TRUE String TreeApp 20 Rugged constructor none IF_ICMPGE FALSE int Password 4 Smooth private never called IFEQ FALSE int XMLParser 9 Rugged constructor none IFNONNULL TRUE String MapClass 33 Smooth public never called IFGT FALSE double
We want to know where there is a difference between, for example, the method call of a smooth LA and the method call of a rugged LA. Note that this is only a sample to be shown here. When I apply the Kruskal-Wallis test with
Branch_type, I get the following result:
Kruskal-Wallis chi-squared = 33.657, df = 15, p-value = 0.003803
While the result of
Kruskal-Wallis chi-squared = 85.377, df = 4, p-value < 2.2e-16
My question is what does the chi-squared mean? How does it indicate the significant difference between the groups? and is it really correct to say there is a significant difference between, for example, the method call of a smooth LA and the method call of a rugged LA?