Question 3

This question also concerns a study that was introduced in Assignment 2

An article by Holland et al “Does home based medication review keep older people out of hospital?” (British Medical Journal 2005; doi:10.1136) concerned the reporting of evidence obtained through a randomised controlled trial intended to investigate this question. Participants were all patients aged over 80 who had experienced an emergency admission to hospital (for any cause), were prescribed two or more drugs on discharge and were returning to their own home or warden controlled accommodation.

Participants were randomised to receive either:

Intervention: two home visits by a pharmacist within two weeks and eight weeks of discharge to educate and aid patients with their medications, or

Control: standard care. 

Analysis focused on 415 individuals randomised to the intervention and 414 individuals randomised to control. The primary outcome measure was the number of emergency re-admissions to hospital at 6 months.

The average number of re-admissions was 0.56 (SD = 0.87) for participants randomised to the intervention and 0.43 (SD = 0.73) for participants randomised to control. 

(a) Assuming the number of re-admissions is a continuous variable, test for a difference in (population) average number of re-admissions for participants randomised to the intervention and (population) average number of re-admissions for participants randomised to the control. Use a two-tailed test and assume a Type 1 error level of 0.05 (i.e. a = 0.05) was pre-set as acceptable. Show your working.

(b) State your conclusion clearly so that an individual without your statistical knowledge could understand the results.

(c) Without any calculations, briefly explain how the results of a test of a one-tailed alternative hypothesis might differ from those found in (a).