Linked Questions

This question is about three-way interaction and the possibility of applying without second lower terms with keeping the main variables in the equation not like the other questions. In fact the other ...

I'm applying growth curve modelling and am interested in modelling a three-way interaction between predictors A x B x C. From what I remember a condition for modelling three-way interactions in ...

I am testing the effect of commodity demand shocks to the foreign exchange market. Because my hypotheses include three-way interaction effects, I test my hypotheses using hierarchical regression model....

Is it ever valid to include a two-way interaction in a model without including the main effects? What if your hypothesis is only about the interaction, do you still need to include the main effects?

I have a (mixed) model in which one of my predictors should a priori only be quadratically related to the predictor (due to the experimental manipulation). Hence, I would like to add only the ...

If I were interested in fitting two-way interactions between a linear explanatory variable $a$ and another explanatory variable $b$ that has a quadratic relationship with the dependent variable $y$, ...

I have a triple interaction: AxBxD, where A and B are continuous variables and D is a dummy. My regression is Y = A + B + AxB + AxD + AxBxD In this case, do I HAVE TO include BxD also? In theory here ...

I am testing an interaction effect where $X$ and $Y$ are continuous variable and $M$ (Moderator) is a categorical variable (effects coding $+1$, $-1$). I have no clue about how to do a post-hoc ...

If I create a mixed-effects linear regression model similar to the following (using the lme4 package in R), where all of the fixed effect variables are continuous: ...

I have a data set with sales as $Y$ and total retail shelf space ($x$). I want to investigate the diminishing return, i.e. whether additional shelf space would contribute to more sales. I did ...

I have read the previous discussions on interaction effects and main effects, and I have a question on the subject. I am running a destination choice model (multinomial logit), and I have one ...

I do a rige and lasso regression on a train data set and get the lambdas via cross validation and evalute the prediction ...

Different questions here deal with the problem of whether to include main effects in interaction models, for example here, here and here (for the opposite problem, omitting interaction coefficients ...

I am running a series of mixed effect models, which include both linear and quadratic term of a variable T (continuous) and the main IV I (categorical), and facing a dilemma. Model 2 include ...

I am running several phylogenetic least squares analyses in R, where I'm taking an existing data set for several species, and adding two new species for which I have data. I want to do is test whether ...