1. M

    Centering IVs for checking interaction effects in regression analysis

    Attention: I have just skimmed an article (Echambadi, R. and Hess, J.d. (2007) Mean-Centering Does Not Alleviate Collinearity Problems in Moderated Multiple Regression Models, Marketing Science 26 (3), 438-445) which clearly states that the centering of the IVs does not impact the results of a...
  2. M

    Logistic Regression: Testing for interaction effects with many covariates

    Hello everyone! As topic states, I am running a logistic regression with quite a lot of independent variables (23). There are a lot more candidate variables but this is the best model I ended up with. I would like to know if there are any possible interaction/synergy effects among them, but...
  3. M

    how to do a contrast analysis for an interaction between two within subjects effects?

    Hello! I have a quite simple data pattern but find it hard to test a specific contrast I expected. I have 2 within subjects factors, each with two levels. Let's call them reward (high vs. low) and task pressure (high vs. low), while the dependent variable is performance (see the example GLM...
  4. J

    Interpreting main effects in long. mixed model when interactions w/ time are in model

    I am running a mixed effects longitudinal model with linear and quadratic time effects and a continuous outcome. I have a covariate that has a significant interaction with time-squared, so obviously the linear interaction and its main effect are left in the model. When interactions are in the...
  5. E

    Interaction NS but Main Effect becomes Significant?

    Hello, I have a quick question to anyone who might be able to help me! I am running a random-effects multilevel regression model, looking at the effect of Parental Investment scores on children's height. For various reasons, the investment scores have been coded into binary; High and Low. I...
  6. C

    measuring interaction effects

    I've spent months studying statistics texts, and I just cannot figure out how to do the following: I've got categories distinguished by some characteristic, say M vs. F, and then each of those categories has been assigned to one of two groups, say the treatment and the control group in an...
  7. D

    MANCOVA interaction question

    Hi, I have what is probably a simple (or self-explanatory question). I used a MANOVA with three DV's, two IV's and about 6 covariates. I found significant effects where I expected them, but I also expected to see a significant interaction between my two IVs. However, when I plot them, it LOOKS...
  8. S

    Polynomial interaction in a mixed-design ANOVA

    My analysis includes a between-group factors (condition [control vs. experimental]) and several within-subjects continuous factors (cholesterol, glucose, mass). The within-subjects factors were measured, for both groups, once a month over 5 months. I'm interested in seeing whether there was a...
  9. S

    Interpreting hree way interactions

    I'm trying to interpret two significant three-way interactions. I've used hierarchical regression to analyse my data, and I have come up with two significant three-way interactions. My DV is continuous. My IVs are continuous (AAA) and 3 categorical (BBB, CCC, and DDD). This is my model...
  10. A

    looking for interaction with logistic regression with dichotomous DV

    marginally significant regression, only interested in significant interaction Hi, I'm looking at my data for a 2x2 design with a dichotomous DV. Specifically, I want to know whether there's an interaction--I don't care about main effects. I ran a logistic regression in Stata (logit) with...
  11. A

    Significance of Simple Slopes in a 2-way interaction

    I have used simple slopes to test a two-way interaction in a regression model. However, I get 1-tailed and 2-tailes significance results. It is my understanding (based on some reading) that 1-tailed is used in this situation. But how does one decide that or even explain it? Please help me...
  12. W

    Can you have a significant 3 way interaction without a corresponding 2 way interactio

    Hi all, I have found a signficant 3 way interaction (X by Y by Z) using MANOVA, but do not have any significant 2 way interactions (X by Z -or- Y by Z) involving relevant factors; is this possible? If so, how? Thanks, Drew
  13. D

    testing for the change in correlation between 2 variables over a 3rd linear variable

    I have a hypothesis that the strength of correlation between two continuous variables will decrease with higher levels of a third variable. To give an applied example of the problem, looking at the correlation between mothers weight and their adult child's weight, I expect the correlation to...