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Evaluating Statistical Reports · Part 4 of 5
6 exam-style questions with model answers, plus 8 quick multi-choice questions — every question on this part of the 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 learning happens.
Explain the difference between random selection and random allocation, and state what each allows a study to claim.
A study finds that children who attend early childhood education score higher in literacy at age 8. The report concludes that early childhood education raises literacy. Explain why the design does not support this, and describe a study that would.
A company reports: 'We offered all 1 200 staff an optional four-day working week. The 380 who took it up recorded 11% higher productivity over the following six months than those who stayed on five days. The four-day week raises productivity, and we recommend it industry-wide.' Assess this report with respect to its conclusion.
Define a confounding variable and give an example for the observed association between the number of firefighters at a fire and the amount of damage caused.
A study reports that people who eat breakfast weigh less than those who skip it, and concludes that eating breakfast prevents weight gain. Give two alternative explanations for the association and explain each.
A regional health board reports: 'Since our free flu vaccination programme began in the 20 suburbs with the highest hospital admission rates, admissions in those suburbs have fallen by 14%, while admissions across the rest of the region rose 2%. The programme is working and should be extended region-wide.' Assess the causal claim.