MatchingBMJ 2009; 339 doi: https://doi.org/10.1136/bmj.b4581 (Published 12 November 2009) Cite this as: BMJ 2009;339:b4581
- Philip Sedgwick, senior lecturer in medical statistics
- 1Centre for Medical and Healthcare Education, St George’s, University of London, Tooting, London SW17 0RE
Researchers used a matched case-control study design to investigate whether mobile phone use was associated with the development of glioma, a malignancy of the central nervous system.1 Cases and controls were matched for age and sex. Information about potential risk factors was collected using a self report questionnaire.
Which of the following statements, if any, are true?
a) Matching reduces assessment bias of the potential risk factors
b) Matching adjusts for the effects of age and sex as confounding variables
c) Matching eliminates allocation bias
d) Matching reduces recall bias
b—In the above study, two groups of individuals were selected on the …