Linked Questions

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1answer
2k views

Interaction Suppresses Main Effects in Repeated Measures GLM? [duplicate]

Possible Duplicate: What if interaction wipes out my direct effects in regression? I have three hypotheses within my experiment, and interpreting the interaction in relation to the rest of the ...
0
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1answer
1k views

Excluding the components and only including the interaction term in a logistic regression? [duplicate]

Possible Duplicate: What if interaction wipes out my direct effects in regression? We have a question regarding a regression we are working on. We have two dummy variables, net income (If net ...
1
vote
1answer
59 views

ANOVA - Adding interaction term changes a main effect to being insignificant. How can that be? [duplicate]

UPDATE: I don't think the single posted answer is correct. When I run summary(lm(DependentVar ~ IndVar1 * IndVar2, data = Data1)) the first listing is IndVar11 @ p = 0.113, and the four IndVar1:...
1
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0answers
183 views

How to interpret an insignificant main effect that became significant at the presence of interaction effects in moderated regression analysis? [duplicate]

Possible Duplicate: What if interaction wipes out my direct effects in regression? I did hierarchical regression analysis on my data due to having interaction effects in my research model. All ...
63
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4answers
60k views

Does it make sense to add a quadratic term but not the linear term to a model?

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 ...
31
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3answers
42k views

Why could centering independent variables change the main effects with moderation?

I have a question related to multiple regression and interaction, inspired by this CV thread: Interaction term using centered variables hierarchical regression analysis? What variables should we ...
14
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3answers
5k views

Removing factors from a 3-way ANOVA table

In a recent paper, I fitted a three-way fixed effects models. Since one of the factors wasn't significant (p > 0.1), I removed it and refitted the model with two fixed effects and an interaction. I'...
5
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2answers
4k views

Interaction suppresses the main effect? How to interpret it?

I have a simple model without interaction and it stated significant effect for all the explanatory variables (continuous variable rok and categorical variables obdobi (levels hn and nehn) and kraj: <...
1
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2answers
3k views

Interpreting the changing significance of a variable in a Logistic Regression

I am testing the relationship between two variables (Similarity index; Years patenting) on a binomial dependent variable via a Logistic regression in SPSS. I tried two models as you can see bellow in ...
9
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1answer
2k views

Estimating Multilevel Logistic Regression Models

The following multilevel logistic model with one explanatory variable at level 1 (individual level) and one explanatory variable at level 2 (group level) : $$\text{logit}(p_{ij})=\pi_{0j}+\pi_{1j}x_{...
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1answer
2k views
6
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1answer
5k views

How to interpret the significant interaction of two non-significant main predictors?

I have two non-significant main binary variables in my binary logistic regression model, but their interaction is significant. The variables are centered and no multicollinearity is the case (all VIFs ...
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1answer
3k views

Logistic regression: my main effects lose significance when I add my interaction effects. Why?

I have a dichotomous dependent variable for a 2x3 experiment. There are about 30 observations in each cell, for a total sample size of about 180. Each person was only in one cell. The dependent ...
2
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3answers
687 views

How to test for main effects in 2x2 factorial design with categorical outcome

The problem I have is as follows: I have a clinical trial based on 2x2 factorial design (four treatment combinations, balanced design)comparing treatment A with treatment B, where the primary outcome ...
3
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2answers
115 views

Multiple Regression: Two Binary ind. vars. - Can an interaction term be significant, when the main effects are not?

I think this is a simple question, but I'm having difficulty coming up with a test or example for this. Consider lm(A ~ B*C, data=D) where A is continuous; B and C ...

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