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An in-depth exploration of confounding in epidemiologic studies. It covers the concept of confounding, methods to prevent and evaluate it, and the criteria for confounding. The document also discusses various methods for controlling confounding, including matching, restriction, and randomization, and evaluating confounding through stratified analysis and multivariate analysis.
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LearningObjectives • Understand^ the^ concept
ConfoundingA situation in which effectsof two^ risk^ factors
are mixed in the occurrence ofthe health problem understudydocsity.com
RestrictionStrength •Straightforward•Convenient if criteria arenarrow•Inexpensivedocsity.com
RestrictionLimitation • Reduces the number of subjectseligible to participate • Difficult if criteria are not narrow • Does not permit evaluation ofassociation between exposure andoutcome for varying levels offactordocsity.com
RandomizationStrength • Controls confounders even thoseunsuspected • Study groups are comparable • Permits evaluation of
association between exposure and outcome forvarying levels of the factordocsity.com
RandomizationLimitation • Not easy to perform • Ethical problems • Expensivedocsity.com
MatchingStrength • Appropriate when sample sizeis small^ and^ matchingvariables are limited • Study groups are comparabledocsity.com
MatchingLimitation • Difficult, expensive and timeconsuming to find comparisonsubjects • Matching on a particularvariable prohibits studying itsassociation with the outcomedocsity.com
Stratified AnalysisStratification^ is^
a^ technique used to control confounding inthe analysis stage that involvesthe evaluation of the associationwithin homogeneous categoriesor^ strata^ of^ the
confounding factordocsity.com
StratificationStrength • Easy for limited variables withlimited number of categories • Permits evaluation of confoundingand interaction • Permits evaluation of associationbetween exposure and outcome forvarying levels of the factordocsity.com