Talk:Interaction variable

hi, sorry, if my example is biased towards my experience... if it doesnt make sense or someone thinks they can simplify it further please do :) Tmov81 02:27, 12 December 2006 (UTC)

Interaction and multicollinearity

Including interaction variables doesn't cause problems with multicollinearity (except maybe in some rare and not very noteworthy cases). If you have two variables in a regression model and you multiply them together and use the product as a third variable, the third variable can not be collinear with the other variables because it is their product.--Bkwillwm 23:05, 29 August 2007 (UTC)

Huh?

The second sentence in this article says an interaction variable is formed by multiplying two predictor variables.

But then later in the article it's talking about categorical predictors, which clearly cannot be multiplied.

Now someone's proposed merging this with interaction (statistics). And that article also begins by talking about multiplication of two predictors, just as if it's about that particular form of interaction rather than about interaction in general.

What a mess.

Michael Hardy (talk) 01:28, 13 May 2009 (UTC)

I think it's assumed that the categorical predictors would be represented with dummy variables, which can be used to make interaction variables.--Bkwillwm (talk) 01:38, 13 May 2009 (UTC)