Matching

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Requiring assets and liabilities of an insurance company to go up or down together on a proportional basis. The duration of the asset and liability should be approximately the same. For example, an insurance policy of 12 months in duration should be identified with an asset that matures in 12 months. As interest rates go up, thereby requiring the insurance company to pay a higher return to its policyholders, the interest earned on investments should go up on a proportionate basis.

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adj

Definition: corresponding, equal
Antonyms: clashing, different, uncorrespondent, unequal

Matching is a method used to ensure that two study groups are similar with regards to "nuisance" factors that might distort or confound a relationship that is being studied. Consider a study designed to explore the possible effect of asbestos exposure on the risk of lung cancer. It is known that smoking increases the risk of lung cancer and that asbestos workers are more likely to be smokers than the general public. Smoking, therefore, confuses or confounds the asbestos-lung cancer relationship. In order to eliminate the confounding effect of smoking in a case-control study, one could ensure that the diseased and control groups had equal proportions of smokers.

Matching can be implemented using two main approaches: pair (individual) matching and frequency matching. Pair matching links each member of the case group to a member of the control group with similar characteristics. This type of matching is most commonly seen in studies using twins or paired body parts (e.g., a study of ocular disease in diabetes). Analysis in pair matching often uses the McNemar chi-square method. Frequency matching is more commonly used. The control subjects are chosen to ensure that the frequency of the matching factors is the same as found in the case group. Frequency matching can be implemented in various ways, including category matching, caliper matching, stratified random sampling, or a variant of pair matching.

Matching is most commonly used in case-control studies, although some researchers also use it in cohort studies. Theoretical analysis has shown that matching in cohort studies completely controls for any potential confounding by the matching factors without requiring any special statistical methods. There can be a loss of statistical power, however. On the other hand, in case-control studies matching does not completely control for confounding, thus requiring the use of statistical methods such as the Mantel Hanzel approach, standardization, or logistic regression. There can be substantial loss of power if a case-control study matches on a factor which is not actually a confounder.

The role of matching in epidemiological research is controversial. Many epidemiologists routinely match on age and sex, even when they are not confounders. This practice is to be discouraged. Since a matched case-control study still requires a complex statistical analysis and might reduce statistical power, an argument can be made that matching in case-control studies is not desirable (unless the distribution of the matching factor in the case group is extreme).

As an example of matching, consider a case-control study of the role of dietary factors in the etiology of lung cancer. Given the strong effect of smoking on lung cancer risk, and the relationship of smoking with low intake of fruit and vegetables, one might design a case-control study that matched on smoking status. Each new case would be classified into a smoking category (e.g., never smoked, past smoker, mild, moderate, or heavy smoker). Then, a control subject would be recruited who had a similar smoking history. Although this method appears to be a form of pair matching, it would be analyzed as a frequency matched study.

(SEE ALSO: Case-Control Study; Cohort Study; Epidemiology; Statistics for Public Health)

Bibliography

Kleinbaum, D. G.; Kupper, L. L.; and Morgenstern, H. (1982). Epidemiological Research: Principles and Quantitative Methods. Belmont, CA: Lifetime Learning Publications.

Rothman, K. J., and Greenland, S. (1998). Modern Epidemiology, 2nd edition. Philadelphia, PA: Lippincott-Raven.

— GEORGE WELLS

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A system of matchboards, or of sheets of wood veneer, arranged to emphasize grain pattern, as in book matching or herringbone matching.

matching, 2

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Connection of two components or circuits so that maximum power is transferred between the two.

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Dansk (Danish)
adj. - tilsvarende, matchende

Français (French)
adj. - assorti

Deutsch (German)
adj. - passend

Ελληνική (Greek)
adj. - ταιριαστός, εναρμονισμένος, όμοιος

Italiano (Italian)
intonato, dello stesso colore

Português (Portuguese)
adj. - correspondente

Русский (Russian)
согласование, подгонка

Español (Spanish)
adj. - que hace juego

Svenska (Swedish)
adj. - passande

中文（简体）(Chinese (Simplified))
相配的, 一致的, 相称的

中文（繁體）(Chinese (Traditional))
adj. - 相配的, 一致的, 相稱的

한국어 (Korean)
adj. - 잘 맞는

日本語 (Japanese)
adj. - 合っている

עברית (Hebrew)
adj. - ‮מתאים‬