## A.11 Answers to Lecture 11 tutorial

### A.11.1 Answers to Sect. 11.6

$$t$$-test: Age as it is the only quantitative variable. The rest would use a chi-square test. Between the ‘alive’ and ‘dead’ groups, there is evidence that the proportion with diabetes is different and whether or not a (prosthetic) limb was fitted.

### A.11.2 Answers to Sect. 11.7

1. P: school age children with ambulatory cerebral palsy; O: In this case, the hand-writing legibility; C: Between scores made when using standard and specialty furniture; I: The furniture configurations imposed. 2. True experiment, as treatments were imposed (experiment), and the researchers allocated children to the groups (true experiment). 3. Unit of observation: Each students. Unit of analysis: Each student, as the two measurements from each student are related to the same person. The students are compared. So this is a paired analysis. A paired-$$t$$ test. 4. Blinding not used, as students would know the desk configurations were different. No blinding, so double blinding is not used. However: The assessors are blinded to the intervention, as assessor unaware of furniture configuration, so assessor does not influence outcomes (unintentionally). 5. Sample mean: $$30.7$$; $$s=3.3$$. 6. Standard errors $$\text{s.e.}(\bar{x})=3.3\div\sqrt{30} = 0.60249$$; the approximate CI is $$30.7\pm(2\times0.60249)$$, or $$30.7\pm 1.2$$; from $$29.5$$ to $$31.9$$. 7. The sample provides no evidence (paired $$t$$: $$-0.30$$; $$\text{df}=29$$; two-tailed $$P=0.77$$) of a population mean difference between the handwriting legibility when performed using standard ($$30.7$$; standard deviation: $$3.3$$) and speciality furniture configurations ($$30.6$$; $$3.3$$; 95% CI for the difference from $$-0.8$$ to $$0.6$$). 8. No.

### A.11.3 Answer to Sect. 11.8

1. P: Medical ‘teams’ working in paediatric resuscitations; O: Number and type of drug errors; C: None; I: None. 2. Descriptive. 3. Prospective observational. 4. For example: Study is only a mock (not real) situation, due to ethics. Hawthorne effect: subjects know they are being watched.