What is a moderating variable?
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Moderating variable is a variable that changes (increases or decreases) the otherwise established effect of the independent variable upon the dependent variable. So, if we look at the linear relationship where variable X supposedly causes or affects the variable Y, a moderator variable M would somehow alter the strength of that relationship.
Example / Application
Application: For example the video shows the Asch experiment where we can see the volunteer’s answers being affected by the answers of actors that surround him. The results of the experiment revealed that the number of wrong answers given by the actors (X variable) affect the number of wrong answers given by the actor (variable Y). This is not shown in the video, but if we were to replicate the exact same experiment with a female volunteer and found that her answers (Y variable) were not affected by actors’ answers (X variable), then we could say that gender is a Moderator (M) in this case.
Field, A. (2006). Discovering Statistics Using SPSS: Second Edition. London. Thousand Oaks. New Delhi. Sage Publication