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Questions tagged [interaction]

A situation where the effect of an explanatory variable may depend on the value of another explanatory variable.

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Why does it not make sense to compute effects for lower-level interactions in the absence of higher-order interactions?

The documentation of effects package says "If asked, the effect function will compute effects for terms that have higher-order relatives in the model, ...
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55 views

Plotting interaction of categorical predictor and continuous modifier

I fit a GEE model examining the interaction between my predictor: heading quartile (categorical- dummy coded) and a moderator variable: head circumference (continuous). I would like to visualize the ...
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Can polynomials, interaction variables, and autoregressive variables trigger exogeneity issues in regression?

I would think the introduction of the mentioned types of variables would introduce exogeneity issues in regression models. However, in such circumstances are these exogeneity issues material, or can ...
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Separate Models vs Flags in the same model

I have customer data from 2 brands. The data structure are the same, but I expected the customer behaviour to be different in different brand. So I could train 2 models, 1 for each brand, or I could ...
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Difference between tensor product and main effects plus interaction in mgcv [duplicate]

I was under the impression that using te and adding the main effects with s plus the interaction with ...
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1answer
63 views

Non-parametric tests for interaction effects

I have two datasets that are both organised as follows: an algorithm calculated a quality score (Q) of a specific image (image) that was processed using a certain algorithm (method). One has 315 ...
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How do I specify an outcome variable (y) as count data using a poisson regression in a multilevel model?

I have three variables with multilevel data: Level 1 DV: deviant behaviour Level 1 IV: negative affect Level 2 IV: consideration of others (personality trait) Here is my model: ...
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135 views

Problem understanding the interaction term of mixed effects model

I have a question regarding the meaning of an interaction term in a linear mixed effects model. Considering the following experiment (similar to a real one I have): there are three sites, each with ...
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370 views

how do I plot interactions with continuous and categorical predictors in mixed models?

I'm very unsure how to plot mixed-level data consisting of a mixture of categorical and continuous predictors, so any help would be appreciated. This is the data ...
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34 views

Log-transformed DV and coefficient of interaction term

I am having difficulty interpreting the significance of positive tone (measured as percentage of words in a sentence that are positive in tone) for females and males. The following is the regression ...
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48 views

GLM - interacting predictors for which the mediator only applies to one type of outcome

I am running a simple GLM with an interaction of the two main predictors. The outcome (dependent) variable is binary and takes the value of 1 when the product is ...
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22 views

Interaction between covariate and 2-level within-subjects factor is of research interest. How to test

I'm interested in interpreting the interaction between a continuous variable (C) with a dichotomous within-persons factor (A) on a continuous DV (DV). What is the best overall test of this? Would it ...
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54 views

Interpretation and practical significance based on multiple linear regression coefficients

I am having difficulty articulating the practical significance of positive and negative tone in job application cover letters for male and female job candidates. I obtained the following linear ...
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Different significance in GLMM interactions

I am confused about different significance results obtained in GLMM's. First, my set of relevant variables: ...
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17 views

Accounting for Interaction between Independent variables

Is there some trustworthy resource on effect of interactions if not accounted for. Especially the situation is often, let's assume heart surgery, age, gender and logistic euroscore(derived from age ...
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1answer
112 views

GAM interaction- how to interpret

I am working with a GAM model (based on a negative binomial distribution): model_n = gam(y ~ x1 +x2+ x3+x4 + s(x5)+x6+s(acc, by=ses)+x7+x8+ x9+x10, data=totalfinals, family=negbin(3)...
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Categorical variable interaction compared to individual regressions

We are examining our understanding of interaction terms in categorical variables. We have a three category variable, and the model is: $y=\alpha+\beta x+\beta_0x_0+\beta_1x_1+\beta_2xx_0+\beta_3xx_1$ ...
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30 views

Two-way interaction term and simple slope

In my study, I am looking at gender interaction with an independent variable. In the fitted linear regression, if the gender*var1...
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43 views

How to properly test simple effects: factor recode or data subsetting

I have seen people test their simple effects in two different ways and would like to know which is the correct one and why. The two methods are briefly explained below: recoding method: Involves ...
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How to do simple slope analysis for interactions in zero-inflated negative binomial regression in r?

I used the function 'zeroinfl' from the 'pscl' package to fit a zero-inflated model with negative binomial distribution (zinb). Results show significant interaction effects and I should do simple ...
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1answer
57 views

Log response ratio of means not agreeing with linear mixed model output

I have a linear mixed model structured like so: Richness~Time*Treatment+(1|Site) Time has two levels (Pre and Post) as does Treatment (Treatment and Control). ...
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82 views

How to evaluate all possible contrasts of an interaction effect

Let's say I have an experiment where I pair people up with either individuals of the same political orientation, or different. I track before and after measures of a respondent's belief in global ...
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44 views

What's the most intuitive way to decide if interaction exists between 2 categorical variables in regression in R?

To discern interaction between categorical and numerical variable, one can look at the slope change. What's an intuitive visual way to detect or deny interaction between categorical variables? ...
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Testing for interaction between two categorical independent variables and a dependent variable

This is a contrived example for clarity, but it reflects a real problem that I'm dealing with: Say that I want to analyse miles-per-gallon (ratio) for cars of different color and interior type (both ...
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181 views

Difference-in-difference effect with triple interaction

I added an image of the regression output I could use some help with, as I am trying to recreate this but with data from a different time period. This is the result of a difference-in-difference ...
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51 views

The right statistical method to measure a complex synergy

In order to measure multidimensional effects, it can be common to compute a score, as a combination of unidimensional factors. For instance, one could compute a score ...
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3answers
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Examples where A increases with increasing B or C, but decreases when both B and C are increased together

I have a vague memory that this relationship is possible, but I can't think of any examples off the top of my head. Is there a canonical or common example(s)? I am imagining that in two independent ...
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27 views

Which statistical test to determine interaction effect?

I conducted an experiment to determine the effect of blood type on blood cell interactions with proteins of differing blood groups and want to determine if there is an interaction effect for the ...
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1answer
29 views

interaction between 4-level categorical variable and a continuous moderator

I'm trying to find a way to investigate whether religiosity correlates positively with helping other people, and whether this correlation is different depending on a 4-level manipulation (in my design,...
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Linear Regression: Why do the coefficients change on the original IVs when you interact them, and add that new interacted-variable to the model?

Basically I want to know how the 'constant' value differs in each of the following models: Model 1: DV=income; IV1=gender (0=male, 1=female); IV2=location (0=east, 1=west) Here, I understand the ...
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How to Interpret Co-Linear Interaction Term?

I am looking to model transit ridership based on demographics at the stop level. For each stop, I know: ONS: Total boardings per day - averaged over the number of times a bus pulls up at the stop ...
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1answer
49 views

Interacting treatment variables with independent variables in matched samples

Can we interact the treatment variables with independent control variables that have been used for matching? I have a binary treatment variable called 'medicine'. It indicates whether a person ...
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2answers
417 views

Why and how does adding an interaction term affects the confidence interval of a main effect?

I was wondering why, in a regression model including an interaction term, the confidence interval of one of the main effects becomes wider. Consider this Cox regression, where the variable IR_BMI27 ...
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184 views

What is a reference level for an interaction of categorical variables in glmer?

I want to see whether there is an interaction effect between "session" and "structure" on participants’ accuracy. For this I run a glmer model: ...
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Simple main effects - R

This is a simple question yet I cannot find a definitive answer anywhere. When running a two-way anova in R, I get a significant interaction. I am aware that because the interaction effect was ...
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How to conduct a moderated multiple regression with two (or more) moderators?

I've been trying for a while to understand how to perform this type of analysis, but I can't seem to find any literature or even forum posts about it, so any help or guidance anybody can offer would ...
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34 views

Main effect insignificant: should I estimate an interaction with it?

As the title reveals, does it make sense to estimate an interaction when you already see that a main effect is insignificantly different from 0 in regression? In my study I am actually interested in ...
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211 views

Moderation in R: Plot moderation for regression model with one interaction and controll variable

I'm testing a moderation using R and would like to plot it. This is my regression model (2 predictors + interaction): ...
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27 views

Modeling interaction between state and action in Reinforcement Learning with Function Approximation

This is a question that has been bugging me for some time: if I'm designing a RL algorithm to find the optimal value-action function Q(s,a), and I want the optimal action to depend on the specific ...
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Should I restate my hypothesis? (interaction)

Suppose I have the following model: $Y = α + β1∗education + β2∗gender + β3∗gender∗education$ Gender = 1 if male (reference group = 0 female) Based on the theory I develop the following two ...
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Is a three-level multilevel model appropriate for my research question?

For a study that is currently in the planning stage we are considering what kind of model would be most appropriate. We are interested in the interactive effect of a drug (vs. placebo) and hormone ...
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27 views

reporting beta coefficient for chunk tests in logistic regression

I have used lrm in the RMS package to construct a logistic regression model with several interaction terms for a recent paper. As part of my strategy, I decided to use Wald Chi-squares on factors ...
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45 views

How to chose covariates to adjust for in a regression analysis

I am running a regression analysis where my primary interest is to see if the outcome differs by the group (treatment vs. control). However, I have some 80 other clinical and socio-demographic ...
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983 views

3-way ANOVA with a significant 2-way interaction. What are my next steps?

I have performed a mixed 3 way ANOVA: Group (2 levels) x Factor2 (2 levels) x Factor3 (2 levels). There was no significant 3-way interaction; however, there was a significant 2-way interaction ...
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32 views

perfect separation after adding interaction term

I am using glm to estimate a model (dependent is dummy). I have two continuous variables that I want to test their interaction. As soon as I add the interaction ...
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21 views

Type-I error adjustment for simple effects when 2x3 factorial ANOVA interaction only is significant

I have found several questions and answers that skirt around my problem but I haven't been able to deduce a clear solution. My situation is this: I ran an experiment with a 2x3 factorial design (call ...
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Testing if a correlation between two ordinal variables depends on a third variable

I have two ordinal variables : $y_1$ (a dummy) and $y_2$ (five categories). I know they are correlated, but I have reasons to believe this correlation depends on a third variable ($z$). An interaction ...
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30 views

Test significance of combined interaction coefficients

Is there a way to test the significance of combined (interaction) coefficients in R? I have a panel regression model of the following (simplified) form: yi,t = b0 + b1xi,t + b2xi,t*phase_1t+ b3xi,...