D.33 Answers: Reading research

Answers to exercises in Sect. 36.4.

Answer to Exercise 36.1: 1. Not ecologically valid. 2. Ethical. People understand that sometimes unexpected things happen. 3. Convenience; self-selected. However, nothing obvious to suggest the people in the study would record different accuracies than people not in the study. 4. Inclusion criteria. 5. Paired \(t\)-test. 6. Evidence in the sample that the mean difference in step-count between the two methods cannot be explained by chance: likely is a difference. 7. From the given information: Probably valid.
Answer to Exercise 36.2: 1. Students at that university (QUMS). 2. A random sampling method has been used,
so results should be generalisable to the population (students at that university). 3. \(t\)-test comparing two means. 4. Three groups. Null hypothesis: the population mean hearing loss score is the same in all three groups. Alternative hypothesis: the mean hearing loss score is not the same in all three groups. 5. Standard error: \(\text{s.e.}(\bar{x}) = 3.08/\sqrt{745} = 0.1128\); CI is \(19.8 \pm 0.26\). 6. Need the standard error for the difference between two means, which is not reported.