A marine biologist is investigating the effect of a new nutrient-rich feed on the growth rate of farmed Atlantic salmon. She uses an independent groups design with two separate sea cages: one cage is fed the new formula, and the other is fed standard feed.
Explain why random allocation of the salmon fingerlings to the two sea cages is necessary in this experimental design.
689 exam-style questions on AQA A Level Psychology Scientific processes. Each one has a worked solution and a mark scheme showing where the marks go.