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1 vote

Strange interaction term estimate in a logistic regression with a large class imbalance between exposure groups. How to interpret?

My knowledge of the field pushes me to think something is wrong, as I would've expected the OR of the interaction term to be either above 1 or not statistically significant. If the interaction effect ...
Sextus Empiricus's user avatar
5 votes

Strange interaction term estimate in a logistic regression with a large class imbalance between exposure groups. How to interpret?

One problem is that you are relying far too much on significance tests and not showing us all the effect sizes. You say that in separate analysis by levels of X, the X=1 test was not significant while ...
Peter Flom's user avatar
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2 votes

Appropriate way to configure contrasts and interactions in GLM likelihood ratio test

Sections 6 and 7 of the Bioconductor vignette on creating design matrices for gene expression experiments are helpful here, as is Section 3.3.1 of the edgeR User's Guide. A few issues stand out to me ...
EdM's user avatar
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1 vote

Significant pairwise comparisons from emtrends but marginal means are not-significant?

As you know, the emtrends part of the output shows whether the continuous predictor's slopes for each categorical x categorical combination differ from zero and the contrast part shows whether they ...
Sointu's user avatar
  • 1,084
4 votes

Using interaction terms in causal models

I mean is it ok to dig for significant interactions once my effect initially fails to show significance, given no expert / literature knowledge exists about the existence of such interaction effects. ...
Demetri Pananos's user avatar
2 votes

Synergistic effects: what statistics should I use?

Statistics cannot tell you if an interaction is synergistic! You need to characterise the dose-response relationship of both agents and see if both together yields an effect that is greater than ...
Michael Lew's user avatar
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5 votes

Testing the proportional hazards assumption with a time varying covariate

I don't know the origin of the idea that Schoenfeld residuals can't be used for testing proportional hazards (PH) with time-varying covariate values. As Therneau and Grambsch say in Section 4.6: ...
EdM's user avatar
  • 86.6k
0 votes

Difference in stratification, interaction and subsetting Cox Survival Regression

I would combine model 2 with model 1 and text the interaction. Model 2 tests for the interaction term but assumes the same baseline hazard function for men and women.
Abderrahim's user avatar
1 vote
Accepted

How to deal with interaction terms in regression that cannot have a negative product?

Multicollinearity gets a lot of undue attention. As the Wikipedia entry states: Multicollinearity does not affect the accuracy of the model or its predictions. It is a numerical problem, not a ...
EdM's user avatar
  • 86.6k
1 vote
Accepted

How to interpret standardized simple slopes and indirect effects in R with semTools and lavaan?

I found another post that provided some insight on the topic Please note that I just edited that 2022 response (because I am not allowed to rescind an accepted answer). Please read there about the ...
Terrence's user avatar
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1 vote

Interaction with dummy variable: How to access std. error, t value, p value, (and others) for the opposite manifestation of dummy

Question 1. Although you might get the same point estimates within each vs group by deleting the cases in the other vs group, ...
EdM's user avatar
  • 86.6k
3 votes

Estimated marginal means versus model-derived interaction effects

Interaction terms in linear models assess if group effects differ across measurements. A significant interaction suggests the group's influence on outcomes varies at different times. ...
Robert Long's user avatar
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4 votes

What method should be used if the clusters contains different classes?

This problem violates the so-called cluster hypothesis which states that points in the same cluster should generally belong to the same class. Here the clustering appears uninformative for determining ...
Nuclear Hoagie's user avatar
4 votes
Accepted

What method should be used if the clusters contains different classes?

The trouble with your example is that these clusters are not particularly informative about the color you aim to predict. If one cluster were mostly blue, another mostly yelllow, etc, then the cluster ...
Dave's user avatar
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