1. Back Pain Treatment – In a study designed to test the effectiveness of parace

Question

1.       Back Pain Treatment – In a study designed to test the effectiveness of paracetamol (or acetaminophen) as a treatment for lower back pain, 1643 patients were randomly assigned to one of three groups: (1) the 547 subjects in the placebo group were given pills containing no medication; (2) 550 subjects were in a group given pills with paracetamol taken at regular intervals; (3) 546 subjects were in a group given pills with paracetamol to be taken when needed for pain relief. Is this study an experiment or an observational study?

In this case

2.       Blinding – What does it mean when we say that the study cited in Exercise 1 was “double-blind”?

Exercises 3 and 4 refer to the study of an association between which ear is used for cell phone calls and whether the subject is left-handed or right-handed. The study began with a survey e-mailed to 5000 people belonging to an otology online group, and 717 surveys were returned. (Otology relates to the ear and hearing.)

Sampling Method – What type of sampling best describes the way in which the 717 subjects were chosen: simple random sample, systematic sample, convenience sample, stratified sample, cluster sample? Does the method of sampling appear to adversely affect the quality of the results?

4.       Response Rate – What percentage of the 5000 surveys were returned? Does that response rate appear to be low? In general, what is a problem with a very low response rata?

Explanation / Answer

1. Since the patients are randomly assigned to one of the three treatments, the study is an experiment.

2. If we say that the study in 1 was "double blind", it means that not only do the patients know which treatment they received, the three treatments are themselves randomly coded and the personal carrying out the test too does not know whether the treatment is placebo, or paracetomol is given at regular intervals, or only at pain times.

3. It is an example of simple random sample as the respondents are randomly chosen.

4. The low response rate is because of the response being sensitive in nature and there might be an inherent bias.

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