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6 exam-style questions with model answers, plus 8 quick multi-choice questions — every question on the site for this standard, grouped by the 2 pages of notes they come from.
Write a full answer before you reveal the model one — that comparison is where the marks come from. Every block links back to the notes that teach it.
Explain the difference between random selection and random allocation, and state what each allows you to conclude.
A student testing whether a fertiliser increases plant growth puts all the treated plants on a sunny windowsill and all the untreated plants on a shelf across the room. Explain what is wrong with this design and how to fix it.
A class investigating whether a stretching routine improves standing long jump distance decides to measure each student's jump before the routine and again after, comparing the two. Discuss this design.
In a randomisation test with 1 000 re-randomisations, 340 produced a difference at least as extreme as the one observed. Calculate the tail proportion and state what it means.
A student's randomisation test gives a tail proportion of 0.41. She writes: 'The treatment had no effect.' Explain what is wrong and rewrite the conclusion.
A class experiment randomly allocates 40 students to two revision techniques and finds strong evidence (tail proportion 0.006) that one produces higher test scores. A student writes in the conclusion: 'This proves that technique A is better for students, so schools should adopt it.' Discuss.