A marine biologist wants to estimate the mean microplastic concentration in a large lake. The lake has three distinct depth zones (shallow, mid-water, and deep).
Explain one advantage and one disadvantage of using a stratified sampling method, based on these depth zones, compared to using a simple random sampling method for this study.
644 exam-style questions on OCR A Level Psychology Research methods and techniques. Each one has a worked solution and a mark scheme showing where the marks go.