A marine biologist wants to investigate whether a new non-toxic, bio-degradable coating reduces biofouling on underwater data-logging sensors. Biofouling is measured by the mass of organic matter (algae and barnacles, in grams) accumulated on a sensor after being submerged for 12 weeks.
The biologist uses a matched-pairs design across 18 reef locations. At each location, two identical sensors are deployed close to each other:
After 12 weeks, the sensors are retrieved and the dry mass of accumulated biofouling on each sensor is recorded.
A statistical test conducted on the difference in biofouling mass between the two groups is found to be not significant at the 5% significance level.
The biologist is concerned that a Type II error may have been committed.
Explain what is meant by a Type II error in the context of this study.
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.