In a marine biology experiment investigating the effects of water temperature on territorial behaviour, researchers observed two independent groups of male fiddler crabs (Uca pugnax).
The researchers recorded the territorial aggression of each crab using a standardized 5-point visual threat scale (where 1 indicates no threat display and 5 indicates highly aggressive claw waving). They want to determine if there is a significant difference in the aggression ratings between the two temperature groups.
Explain why a Mann-Whitney U U\,U test is an appropriate statistical test to analyze these data, whereas a Spearman's rank correlation coefficient test is not.
121 exam-style questions on AQA A Level Psychology Inferential testing (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.