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Statistical Experiments · Part 3 of 3
6 exam-style questions with model answers, plus 6 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.
In an experiment, the treatment group's median yield is 15 kg and the control group's is 11 kg. State the observed difference.
The treatment group has median 15 kg (box 12–18) and the control 11 kg (box 9–14), on the same scale. Compare the groups and state what still needs checking.
Two students look at the same experiment. One says 'the treatment clearly works because its median is higher.' Explain why that reasoning is incomplete.
An experiment found that the treatment group's median reaction time was 0.04 seconds faster than the control group's.
Write the inference this supports.
In an experiment, the treatment median is only slightly higher than the control median, and the two box plots overlap almost completely.
What should you conclude, and why?
Twenty-four people were randomly allocated to two groups to test whether a stretching routine improves flexibility. The treatment group's median improved by 6 cm more than the control's, with limited overlap between the groups.
Write a full conclusion, and explain what you can and cannot claim.