An investigation was carried out to determine if there is an association between the shell type of hermit crabs and their choice of burrowing zone in a test arena containing microplastics.
A sample of 90 hermit crabs was classified by shell type as either 'Gastropod Shell' or 'Bivalve Shell'. Each crab was placed in a test arena containing three distinct zones: Zone A (microplastic-treated sand), Zone B (pristine sand), or Zone C (rocky substrate). The zone each crab chose to burrow in was recorded.
The researcher decided to use a Chi-Squared test of association to analyse the data. One reason for choosing this test was that the observations are independent (each crab only contributes to one count in the contingency table).
Referring to information about this study, explain two other reasons why it was appropriate to use a Chi-Squared test of association in this case.
Practise AQA A Level Psychology Inferential testing (A-level only) with exam-style questions for A Level Psychology. 123 questions, matched to the AQA A Level Psychology (7182) specification and written in Paper 1, Paper 2 and Paper 3 style. Every question includes a full worked solution and mark scheme, so you can see where marks are awarded rather than just whether you got the answer right.
