A marine conservation group is investigating the effectiveness of environmental messaging. They recruit 80 visitors at a coastal visitor center. Half of the visitors are shown a graphic documentary about the impact of plastic pollution on marine life, while the other half watch a standard, scenic nature documentary. After leaving the center, visitors pass a voluntary beach clean-up station. The researchers record whether each visitor participated ('Signed Up') or did not participate ('Walked Past').

The researcher uses a Chi-Squared test of association to analyse the data. One reason for choosing this test was that the study utilized an independent groups design, where each visitor was only exposed to one of the two documentaries.