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Evaluating Statistical Reports · Part 1 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.
Name the five stages of the statistical enquiry cycle, and state which stage a poor choice of sampling method belongs to.
A supermarket chain reports: 'We surveyed 600 shoppers as they left our Auckland stores on a Saturday. 82% rated our fresh produce as good or excellent, so New Zealand shoppers are happy with our produce.' Identify one weakness in the Plan stage and justify what it means for the conclusion.
A health charity reports: 'We invited members of our online support community to complete a wellbeing questionnaire. 3 400 of 11 000 members responded (31%). Respondents who used our counselling service scored on average 8 points higher on the wellbeing scale than those who did not. Our counselling service improves wellbeing.' Evaluate the quality of this report with respect to its conclusion.
Explain the difference between a parameter and a statistic, giving an example of each.
A polling company states: 'Our sample of 12 000 people, recruited through advertisements on our news website, is so large that the results are highly accurate.' Explain why the large sample size does not justify this claim.
A council surveys transport habits by stopping people in the central city between 7am and 9am on weekdays and asking how they travelled in. It reports: '46% of people arriving in the central city travel by car. Congestion is therefore less severe than commonly believed, and the planned parking expansion is unnecessary.' Assess the quality of this report with respect to its conclusion.