The use of matching as a technique to control for confounding is most appropriate for which type of study?
|A||A large-scale cohort study|
|B||A case-control study with a small number of cases|
|C||A clinical trial with a factorial design|
|D||A cross-sectional study with multiple variables|
a. Matching is a technique used in the design of the study to control for confounding. Subjects enrolled in a study are matched for age, gender, smoking, or any variable that is not being analyzed.
b. This technique is not used for large cohort studies as it would often be too time-consuming, restrictive, and expensive to find a match for each subject entering the study. Controlling for confounding is done in the analysis and a large group is recruited.
c. The technique is mainly used when dealing with small case-control studies where the number of subjects enrolled would be too small to yield statistical results if stratified by subgroups. Randomization is used in clinical trials to control confounding (sample size needs to be large—see question 27).
d. Matchingcannot be used in correlation studies or cross-sectional studies: these are descriptive studies to assess disease occurrence and they do not have control groups to test a hypothesis.