Each question IS NOT worth the same number of marks. The number of marks and a guide to the length of the answer required for each question is shown on the exam paper.
Answer all questions
Read the question carefully – most questions do not require long answers.
Question 1
The table below summarises the results of five clinical trial designed to assess different interventions (A, B, and C) for alcohol consumption (units per month). A mean reduction of 40 units per month is considered clinically significant. Look at the table and answer the questions below
| Trial | Treatment | Cost | Number/group | Difference in units/month | Standard Error of difference | 95% CI for difference | P-value |
| 1 | A | Cheap | 30 | -40 | 40 | -118.4 to 38.4 | 0.32 |
| 2 | A | Cheap | 3000 | -40 | 4 | -47.8 to -32.2 | <0.001 |
| 3 | B | Cheap | 40 | -20 | 33 | -84.7 to 44.7 | 0.54 |
| 4 | B | Cheap | 4000 | -2 | 3.3 | -8.5 to 4.5 | 0.54 |
| 5 | C | Expensive | 5000 | -5 | 2 | -8.9 to -1.1 | 0.012 |
- Which treatment(s) have the largest impact upon alcohol consumption?
[1 marks; 1-2 sentences]
- What is the range of possible values for the effect of treatment B?
[1 marks; 1-2 sentences]
- Which treatment (A, B, or C) would you choose to implement in clinical practice and why?
[3 marks; 3-6 sentences]
[5 marks total for Question 1]
Question 2
- Explain the difference between probability sampling and non-probability sampling
[2 marks; 2-4 sentences]
- Choose ONE of following types of non-probability sampling and explain how you would use this sampling strategy in a study of cannabis use in client being treated for opiate dependence: targeted sampling OR self-selection sampling OR snowball sampling. Make sure you indicate which sampling strategy you have decided to use in your answer.
[3 marks; 3-6 sentences]
[5 marks total for Question 2]
Question 3
Read the abstract from a scientific paper (below) and then answer the three questions that follow. The possible marks awarded for each part of the question are different and are indicated next to each part.
Abstract
OBJECTIVE: This study evaluated the efficacy of brief gambling treatments in patients attending substance abuse treatment clinics.
METHOD: Substance abuse treatment patients with gambling problems (N = 217) were randomly assigned to a 10- to 15-min brief advice intervention addressing gambling norms, risk factors, and methods to prevent additional problems or 4x 50-min sessions of motivational enhancement therapy plus cognitive behavior therapy for reducing gambling (MET + CBT). Gambling and related problems were assessed at baseline and throughout 24 months.
RESULTS: In the sample as a whole, days and dollars wagered and gambling problems decreased markedly from baseline through Month 5; thereafter, reductions in dollars wagered and gambling problems continued to decrease modestly but significantly, and days gambled remained constant. Brief advice significantly reduced days gambled between baseline and Month 5. The MET + CBT condition engendered no benefit beyond brief advice in terms of days gambled but did lead to more precipitous reductions in dollars gambled and problems experienced in the initial 5 months, and greater clinically significant improvements in gambling in both the short and long term. MET + CBT also resulted in initial decreases in self-reported alcohol use and problems but did not differentially impact self-reported illicit drug use or submission of positive samples.
CONCLUSIONS: Gambling problems tend to dissipate over time regardless of the intervention applied, but offering MET + CBT was more efficacious in decreasing gambling than providing a brief single session intervention.
- What was the study design used in this research? [1 mark; 1-2 sentences]
- What were the exposure(s), comparator(s) and outcome(s) of interest? [3 marks; 3-6 sentences]
- What were the main finding(s) of the study? [1 mark; 1-2 sentences]
[5 marks total for Question 3]
Question 4
A researcher designs an experiment to assess the efficacy of a new treatment for dependence on opiates. She recruits participants from a number of addiction treatment services in London and asks them to complete a survey including a range of questions related to their current opiate use and physical health. Participants are then randomised to receive either the new treatment or a placebo. Participants are assessed in the clinic every week for 12 weeks to determine whether they have started using opiates again, and whether they are experiencing any side-effects.
- What type of study design is this? [1 mark; 1-2 sentences]
- Is the data collected for this study retrospective or prospective? Explain your answer. [2 marks; 2-4 sentences]
When the researcher analyses her data she looks at what treatment the participant received (new treatment or placebo), and whether or not they are using opiates at the final clinic visit (“Yes” or “No”). She wants to know whether there is an association between the treatment participants received and whether or not they are using opiates by the end of the study.
- What type of statistical analysis would be appropriate for measuring the association between these two variables? Explain your answer. [2 marks; 2-4 sentences]
[5 marks total for Question 4]
Question 5
Consider a health practice that provides treatment services to people with substance use disorders. Two different types of study are outlined (below) that might be undertaken in this setting to explore the association between substance use, hepatitis C and HIV. For each scenario identify:
- the type of study design;
- the strengths and weaknesses of this type of design;
- why this study design may have been chosen; and
- the sort of question that you might be able to address with the study design.
- Study 1: You are able to undertake blood testing for hepatitis C and HIV, and interview participants about their current substance use, injecting and sexual risk behaviours, using a validated questionnaire.
[3 marks; 3-6 sentences]
- Study 2: In the second study you identify a group of clients with hepatitis C, and a group without hepatitis C. Interviews are conducted with both groups to collect information about their history of substance use (types of drugs used and duration of use) and history of sexual and injecting risk behaviours.
[3 marks; 3-6 sentences]
[6 marks total for Question 5]
Question 6
- You are interested in craving as a factor in relapse during treatment of alcohol dependence. Describe in general terms (a) a qualitative and (b) a quantitative research approach to investigate this association. Consider the aims and types of questions that tend to be answered by each kind of research. How might the studies differ in terms of sample, type of data, and methods of data analysis?
[5 marks; 4-8 sentences]
[5 marks total for Question 6]
Question 7
- A researcher formulates a brief questionnaire to assess happiness. The questionnaire includes 10 questions, each of which is rated on a 7-point scale and it is designed to be completed using a ‘paper and pen’ written format. Before using it in a large scale study the researcher decides she would like to assess the test-retest reliability of this scale. Describe in 2-3 sentences how she could collect data to achieve this.
[3 marks; 2-3 sentences]
- What is the difference between the reliability and validity of a test?
[2 marks; 2-4 sentences]
[5 marks total for Question 7]
Question 8
- How have ethnographic studies of injecting drug use informed public health intervention?
[2 marks; 3-5 sentences]
- What is Publication bias and how can be addressed?
[2 marks; 3-5 sentences]
[4 marks total for Question 8]
Question 9
- What are the main characteristics of clinical trials that ensure interval validity? [3 marks; 3-6 sentences]
- Imagine that you know of two randomised controlled trials comparing intervention A with intervention B. In both these trials it looked like intervention A was more effective, but the difference between the two interventions was not statistically significant. A systematic review is published that concludes that intervention A is significantly more effective than intervention B. Can you explain why this situation might have occurred?
[2 marks, 2-3 sentences]
[5 marks total for Question 9]
Question 10
- What is administrative data (as used for research studies)? [1 mark; 1-2 sentences]
- Give two examples of administrative data. [1 mark; 1-2 sentences]
- What are the complications and limitations of using electronic medical records for research?
[3 marks; 3-6 sentences]
[5 marks total for Question 10]
