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Control Variable

  • In: Encyclopedia of Epidemiology
  • Edited by: Sarah Boslaugh
  • Subject:Public Health (general), Public Health Research Methods , Epidemiology & Biostatistics

In research design, a control variable is defined as a variable that is known to or expected to influence the dependent variable and might also affect the explanatory or independent variable in an analysis, but is not the focus of interest for the researcher. The influence of a control variable may interfere with the main analysis, for instance, by obscuring between-treatment or between-group differences, or creating apparent relationships between variables of interest. Often variables of this type are used to create blocks in an experimental design or stratify a sample. Occasionally, the examination of the influence of control variables is called ‘elaboration of the analysis’ because they are not the variables of main interest in the analysis.

Within the realm of designed experiments, a control variable ...

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