http://psychwiki.com/index.php?title=Talk:Interaction_between_categorical_and_continuous_variables&feed=atom&action=historyTalk:Interaction between categorical and continuous variables - Revision history2020-10-24T02:31:46ZRevision history for this page on the wikiMediaWiki 1.16.0http://psychwiki.com/index.php?title=Talk:Interaction_between_categorical_and_continuous_variables&diff=25932&oldid=prevFlojo: Must center categorical variable as well.2011-03-18T19:18:27Z<p>Must center categorical variable as well.</p>
<p><b>New page</b></p><div>Centering the categorical variable in this case would also be necessary, unless you want the regression to return coefficients that apply to the population of people with a score of 0 on the categorical variable (and since I'm assuming one would code the example categorical variable 1,2, this would be meaningless). See this reference for a good discussion: Kraemer, H. C., & Blasey, C. M. (2004). Centring in regression analyses: a strategy to prevent errors in statistical inference. International Journal of Methods in Psychiatric Research, 13(3), 141-151. doi:10.1002/mpr.170</div>Flojo