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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Categorical x continuous variable interaction in regression?

I have a sample containing two subgroups and I would like to measure the relationship between two continuous variables across the entire group and check if there's an interaction with subgroup. First, ...
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Interaction effect between two categorical variables in piecewiseSEM

I would like to include an interaction effect between two categorical variables in my regressions feeding into a piecewise structural equation model using the package "piecewiseSEM" in R. My ...
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How to interpret change in signficance after adding an interaction?

I'm using a Negative Binomial model to analyses the effect of a scale (NR) and another binary variable (Condition) on a count outcome. When I add both variables to the model as main effect, they are ...
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Difference between an interaction and combining two variables into one with a similarity measure?

Conceptually, what would be the difference between interacting two variables in a regression and combining these two variables into one via a similarity measure? I'm looking at top managers and boards ...
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Controlling for a confounding variable in a graph

I have a small dataset of Hg and stable isotope data (d15N and d13C) over time. d15N and d13C both significantly increase with THg concentrations. However, d15N and d13C also decrease significantly ...
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How to interpret main effect with two interaction terms?

I have three variables in a multilevel model: Relationship Status (0 = single, 1 = not single) Living Arrangement (0 = alone, 1 ...
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Interpreting Interaction Effects - Direction of positive and negative direct and interaction estimates

So maybe I'm interpreting interactions all wrong but the directionality of effects is confusing me. Suppose I have an outcome variable "OV" and two explanatory variables "EV1" and &...
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In a moderated regression does the strength of the moderation effect depend on the strength of the relationship between X and Y?

In a moderated regression predicting Y, is there a relationship between the strength of the moderation effect for the interaction term X*Z and the strength of the relationship between X and Y?
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Interpretation of main effects in case of an interaction in binary logistic regression

I have a question about interpreting the main effects from an interaction in a binary logistic regression model. I used glmer() in R with a model with binary ...
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How to interpret interaction in the absence of main effect? Multilevel Modeling

What is the substantive interpretation of an interaction in the absence of a main effect? Statistically I understand that the interaction modifies the main effect, but how to interpret this from a ...
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What are constraints on including interactions into logistic regression?

I'm assessing effects of age, gender and speech style on the realization of linguistic forms. All the dependent and independent variables are binary categorical. My dataset: When I run logistic ...
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Interpretation of Model with Continuous Interaction Term

Imagine a variable $y$ across $i$ sections, i.e. $y_i$. For every $y_i$ there exist a $x_{1,i}$, a $x_{2,i}$ and a $x_{3,i}$. However, the following relation exists: $x_{1,i} *x_{2,i} = x_{3,i}$. For ...
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How to interpret very different interaction coefficients in correlation and regression

I am analyzing a very simple dataset, with numerical dependent variable y, and independent variable x. the dataset has also z, a categorial variable with 2 levels A and B. If I run the two ...
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Total effect of main variable and it's interaction with dummy

I am going to estimate the following model: y=constant+b1(X)+b2(X)(Dummy) We have daily data from 1990 to 2000. Dummy variable is equal to one for the daily data of year 2000, else zero. b1 is the ...
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How to interpret interaction effects when main effect is not significant?

I ran a linear mixed model in R and included an interaction effect between two predictors. The main effect was not significant, but the interation effect was. Is it possible to interpret this ...
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How to prove that in a linear model with an interaction term, centering the covariates doesn't impact the estimate of interaction coefficient? [duplicate]

So if the model is $y_i = \beta_0 + \beta_1 x_{i1} + \beta_2 x_{i2} + \beta_{12} x_{i1} x_{i2} + \epsilon_i$, how can it be proved that the estimate and standard error for $\beta_{12}$ the same if we ...
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Metafor package: choice of moderator for bias correction

I am doing a 3-level meta-analysis using rma.mv() function. I found a thread about bias diagnostics with an advice to use "regression test for funnel plot ...
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Is it valid to add only one interaction in a model with four main effects?

This may be a silly question, but here it goes: When modelling data, is it valid to add to the model 4 main effects but only 1 specific interaction between two of the variables? or one should look ...
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How to determine economic significance of an interaction term of two continuous variables in an OLS regression? [closed]

Y= Intercept+ Beta1X1+ Beta2X2+ Beta3(X1X2)** I want to determine the economic significance of Beta3 when Y, X1, and X2 are continuous variables, preferably in terms of standard deviation units. Is ...
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Can an interaction term be justified with substantive theory alone?

Let's say we have immense literature theoretical justification to expect that X1 predicts Y, even though X1 contributes only slightly to explaining variation in Y. We want to know if X1 is more ...
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Why are my p-values of my interaction variables so high in Biogeme?

I am trying to estimate a model in Pandas/Python Biogeme. I have a fairly small sample size (N=52). I have a 4 out of 9 significant parameters. Now that I estimated my base model, I am looking to add ...
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Interaction term alters degrees of freedom for main effects in glmmTMB model

I am using the glmmTMB package to test whether the probability of a seed remaining dormant in the soil (binary variable) depends on the population it comes from (fixed effect, 8 levels of population), ...
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How to interpret multiple interactions in lm

I'm wondering how to interpret the summary(lm) output in the context of multiple interactions. Here's some toy data with 2,000 observations, one dependent variable, ...
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Three-way interaction and no two-way interaction

I was wondering in anova whether it is possible to have a three-way interaction without having any two way-interaction. Does it make any sense to hypothesize this? Does it make any sense to ...
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Significant Interaction but non-significant Main Effect: Where to go next

I've just conducted a 2-way ANOVA and Tukey's HSD test, receiving the following results: (Preditors: TREATMENT (Mycorrhizal / Non-mycorrhizal); P_LEVEL (Low / High)) (Response: ROOT:SHOOT ratio) <...
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Interpretation of binomial GLMM with interaction fitted with glmer

I have a glmer model from the R package lme4 with a binomial distribution and I was wondering whether I am interpreting the ...
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1answer
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Best practices for regression when using seasonal data? [closed]

I have a variable $y$ that I would like to model using a set of independent variables $X$. Both $y$ and $X$ are monthly measurements (~10 years in total) and appear to be subject to seasonal ...
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When does construing $M$ as a simultaneous mediator and moderator of a variable's effect make sense?

Hayes (2018) p. 540 writes I will not take a firm position on whether construing $M$ as a simultaneous mediator and moderator of a variable’s effect could ever make substantive or theoretical sense. ...
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interpreting interaction terms in non linear regression

I have a hard time interpreting my coefficients in my nonlinear regression. In particular, I have a negative binomial, with two dummy variables: Treatment and (being) foreigner, outcomes are count ...
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Interpretation of interaction coefficient in PPML with fixed effects

I am estimating a gravity model aiming at evaluating how environmental policies can affect trade patterns. I am using a ppml model using the ppmlhdfe command in Stata.  As identification strategy, I ...
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What models are good at dealing with interactions between features?

I have a data set where I suspect many times attributes are only predictive when interacting with another attribute. What machine learning model would you choose to deal with this issue? Which would ...
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Logistic regression interaction only significant when main effects are removed

I'm interested in understanding if the interaction of a categorical variable (group A or B) and a continuous one (X1) can predict reaction time. I started by testing the main effects plus the ...
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How to interpret interaction effect of two time varing predictors in mixed effect model

I am interested in the effect of a time varying variable on symptom change over time. Simple example: i estimate in a mixed effect model the interaction between time varying predictor X and ...
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Model with interaction completely different than without

I have a regression model with 2 numeric independent variables and I set up a model without an interaction term. This is the result: ...
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112 views

A 2SLS when the instrumented variable has two interactions in the model

I am using ivreg and ivmodel in R to apply a 2SLS. I would like to instrument one variable, ...
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How to obtain the semipartial r squared (sr2) for simple slopes (lows/highs) in regression?

Note: I'm reposting a modified version of this post from Stackoverflow because I didn't receive any response there and I'm thinking that it might be because I'm asking a question about the ...
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Need help interpreting significant two-way interaction and insignificant three-way interaction

So typically I would have no problems with such interpretations. But my design is a little complicated so would appreciate any insight into this. I am interested in looking at the effect of ...
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In mixed three-way ANOVA, how to interpret the 2-way interaction when there is no 3-way interaction?

I'm doing a mixed three-way repeated measures ANOVA. I have a significant two-way interaction A:B (with no significant three-way interaction). My between factor is A (3 levels) and within factors are ...
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Interaction term intuition [duplicate]

Say if we had a case: $y=α+βmale+βeduc+ε$ $y=α+βmale+βeduc+βmale*educ+ε$ let's say that both male and educ are indicator variables. What exactly does the interactive term mean in plain English, ...
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How to best analyse intensive longitudinal data with time-varying moderators?

I'm struggling to find an appropriate way to analyse the model attached with the given data situation (see below). I would appreciate to hear some of your ideas on how to tackle this (and, if ...
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Why, or why not, factor categorical variables in regression modeling?

I'm currently in the midst of running several logistic regression models to test for effect modification (i.e., testing interaction terms) between two categorical variables (sex and age as a ...
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Moderation in cloglog regression

I am testing the effect of climate on task completion and am thinking about including two variables as moderators in my cloglog regression. I am wondering if it makes sense to enter these moderators ...
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Instrumental Variable for Moderator (Causality)

I only know of instrumental variables that causally influence the independent variable and, through the independent variable, are associated with the outcome (making it possible to assume the causal ...
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Equivalence between interaction and second difference measures of heterogeneity

I am trying to understand a paper used by Frank Harrell in his biostats course to demonstrate how NOT to present results from an analysis of heterogeneity of treatment effects (HTE). Frank's point is ...
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How to include an interaction with sex

I am performing linear regression on a dataset and want to include an interaction between sex and another covariate. However, in my model sex is coded as $0$ for female and $1$ for male. If I have ...
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How to find out if interaction of three binary variables is significant?

If I have two binary explanatory variables $A$ and $B$, and one binary response variable $C$- we can find out if $C$ is associated with $A$ or $B$ by creating contingency tables of $A,C$ or $B,C$ and ...
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zero inflated model in R, building the model with pscl, not understanding use of ' | 1'

I have count data with lots of zero. I have done a GLM with poisson distribution, and I think that using the zero inflated model might improve the fit. Now my problem, I have been working with SPSS. ...
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Question concerning modelling an interaction (two continuous variables) with GAM (package mgcv)

I have a question concerning modeling an interaction (two continuous variables) with GAM (package mgcv) where I get different results when I include the main effects or not next to the interaction. ...
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How do you know when to add interaction in the model?

Suppose I'm building a logistic regression model y~ax1 + bx2. How do I know when I may want to think about adding the interaction term, i.e. y~ax1+bx2 +(a*b)x3? Is it purely domain knowledge, or ...
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Interaction-only model over full model: how to get interaction effects for all levels of a factor

I've looked for a question that could possibly cover this but I did not find any. It may be basic but as a R beginner I'm strugling with it. So here it is: I'm running a mixed effect model to test ...

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