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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45 views

What would be the appropriate statistical test for my study?

What would be the appropriate test for a study that has: 2 categorical independent variables with 2 levels each, 1 moderator variable (and would it matter if my moderator is categorical or continuous?...
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0answers
42 views

Causal model: Controlling for moderating effect of confounder (rather than the confounder itself)

My linear regression model can be described by the following causal graph: I want to explain the sign of the causal effect of $X$ on $Y$, but unfortunately cannot measure $Z$ directly. Thus, I can ...
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1answer
196 views

Feature Interaction Strength in Catboost

I was wondering if anyone knew how the feature interaction strength is calculated in the catboost package. The documentation https://catboost.ai/docs/concepts/output-data_feature-analysis_feature-...
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21 views

Can I test for different moderation effects using several regression models or do they have to be included in one?

Let's say I have 8 independent variables A-H which I want to test for significance regarding each of their influences on the dependent variable Z. Now let's say that I additionally suspect moderation ...
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33 views

Does anyone have a reference for the assumptions of moderated hierarchical regression?

I am writing up the results of a moderated regression and need a reference for the relevant statistical assumptions. However, I am having trouble finding one. Would anyone have a reference to share? ...
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28 views

Interpreting the moderator influence from the two-way slope graphs

I am testing the moderation influence of Structural Assurance(SA) on the positive relationship between social influence(SI) which is an independent variable, and the continuance intention(CI) which is ...
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1answer
44 views

Slope is negative but confidence limits contain zero, how do I describe the effect?

I performed an ANCOVA on final height (height4) with initial height as a covariate. Dependent variables: ipc.gm = initial % cover of garlic mustard fence = factor with 2 levels: Fence, Open There ...
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0answers
21 views

Appropriate follow-up test in a 2-way within groups ANOVA

I have a 2 (time1 vs time2) x 2 (drug blood concentration: resting vs. post-exercise) within subjects design. I want to know if the difference between post-exercise and baseline is different at each ...
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0answers
22 views

Is this the correct way to interpret odds ratio for three way interaction?

grateful for any thoughts about this. I'm doing a generalized linear model analysis of a binomial dependent variable (whether the participant gets the correct answer or not). I have three ...
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76 views

ANCOVA significant interactions in R: How do I interpret slopes from interaction plots?

I've got a continuous dependent variable height4, a continuous covariate height, a continuous dependent variable ipc.gm, and a factor fence with 2 levels: Fence and Open. I've got a significant ...
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0answers
19 views

Significant interaction in Mixed-design 2-way ANOVA. How to correct for multiple comparisons?

I have conducted a mixed-design two-way ANOVA (between subjects variable : 2 levels; within subjects variable : 8 levels). I have a significant main effect of between and within subject variables and ...
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0answers
29 views

How to compare growth rates estimated from GLMM?

I've counted aphid populations under 5 different treatments for about 10 weeks. There were 4 replicates of every treatment. I'm interested in comparing the first 4-5 weeks, where the populations ...
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41 views

Interpreting OLS regression with continuous interaction?

I'm a beginner when it comes to statistics and I have a question about how to interpret the results of this OLS model and specifically the interaction of two continuous variables. The following ...
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1answer
45 views

Interpreting categorical interaction terms

I am wondering how to interpret results of interaction terms (see image below). I think to know that the interaction term 1 (IV x potential moderator group 1) depicts the difference of association ...
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1answer
43 views

Testing two potential interaction variables (or potential sources of effect heterogeneity) against each other

I have an experiment I have run, and I am testing for heterogeneous treatment effects (pre-registered and not fishing for any particular result!). Let's call the outcome $Y$ and the treatment variable ...
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0answers
17 views

Analyse interaction/moderators first and then adjust for confounding

In my research I am interested in subgroup analyses. I am looking at a general association between two variables (environment and health outcome) with interaction terms (personal factors, which are ...
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0answers
34 views

How to interpret a two-way interaction in a 3-way interaction model

I am trying to predict y with variables a, b and c. I have two models and I get different results depending on how I fit my model. Model A is the simpler model, in which I exclude variable c. In ...
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3answers
199 views

Multiple regression with dummy variables and interaction term

We have done a multiple regression analysis to see how gender and experience affect salary. We used a dummy variable for gender and then we also added the interaction variable (female work experience)....
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61 views

Interpreting interaction effect between two categorical predictors using linear mixed model

I have read other threads regarding this topic, however, I haven't come across a results table that looks similar to mine (below) so I am seeking some clarification. I am using MIXED (SPSS v25) to ...
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31 views

Comparing Logistic regression Pseudo-$R^2$ between model with Interaction effects and model without Interaction effects

I have two Logistic regression models, one including manually selected (hierarchical) interaction effects between few independent variables and one model without any interaction effects. Both models ...
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48 views

Are conditional effects the same as main effects when using orthogonal contrast codes for categorical predictors?

I ran into a presentation discussing the difference between conditional (or simple) effects and main effects when interpreting regression output in the presence of interaction terms. http://www.lrdc....
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24 views

Three-factor ANOVA

I’m analysing a dataset on contents of flavonoids in different parts of a plant (factor A: leaves, flowers, stems), during different phases of plant growth (factor B: vegetation, full flowering, ...
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29 views

Assess impact on results of participants recruited via additional outreach efforts

I am currently working on a project that evaluates certain study recruitment strategies in regards of increasing participation among different subgroups. One of those strategies is reminder letters. ...
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0answers
46 views

What is the best way to choose interactions between continuous variables for Logistic Regression?

I have a logistic regression model that I am working on for a school project. I have about 55 predictors, all of which are continuous. I am relatively new to the idea of "interactions" between ...
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40 views

Linear regression Interaction Quadratic terms

In linear regression, if I have dependent variable Y and independent variables A and B, where B has a quadratic relationship with Y, and I'm looking for a possible interaction between A and B, I would ...
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1answer
21 views

Significance of the sum of the main effect and interaction term

Consider a simple linear regression with an interaction term: $Y=b_0 + b_1X +b_2Z+b_3XZ$ where $X$ is continuous and $Z$ is a dummy. I want to find out whether $X$ has a significant impact on $Y$ ...
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8 views

Main effect changes after adding interaction term [duplicate]

I have two models: Model 1: Y = b0 + b1X1 + b2X2 + b3X3 Model 2: Y = b0 + b1X1 + b2X2 + b3X3 + b4X2X3 all coefficients are significant in both models but b2 changes from positive in "model 1" ...
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1answer
40 views

multicollinarity issue

I ran a logistic regression moderation analyses and I noticed that with the addition of the interaction term, one of the predictors flipped signs. The variable (X) was previously -.015 and became .006 ...
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1answer
23 views

Is it possible to include an interaction term in logistic model if the interaction term had no observation in some category?

I tried to do a binary logistic regression. y was a binary outcome x1 was an independent variable by 5 categories x2 was an independent variable by 2 categories I found that x1 and x2 had the ...
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1answer
126 views

Does correlation between variables in an interaction matter?

Suppose you fit a model $y = x_1 + x_2 + x_1\times x_2$. Are there any practical implications for estimation of the interaction effect if $x_1$ and $x_2$ are correlated? I understand there could be ...
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1answer
188 views

Interpreting interaction with quadratic term

$Y$ (scores among black students) $\sim X_1 + X_1^2 + X_2 + (X_1 * X_2) + (X_1^2 * X_2)$ ...
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1answer
82 views

Different regression coefficients from statsmodels OLS API and formula ols API

I work at a relatively large Swedish retail company where I am currently performing initial linear regression in order to understand the linkage between dependent variable store sales (number of ...
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0answers
18 views

Interpretation of two dummy variables in interaction with addition of new variables

I have a mixed effects model with an interaction between two dummy variables. Y variable is continuous. My questions: Does the interpretation of the variables included in the interaction (and the ...
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0answers
21 views

Finding Null distribution for gbm interactions

I am trying to determine which interactions in a gbm model are significant using the method described in Friedman and Popescu 2008. My gbm is a classification model with 9 different classes. I'm ...
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2answers
59 views

How do I interpret the linear regression models when significance is lost when interaction term is added

Can someone kindly help me to interpret a model - lm(A ~ sqrt(B) + as.factor(C), data =mydata) which gives a result that B is significantly associated with A (based ...
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1answer
28 views

Is it acceptable to simply plot an interaction instead of performing follow up tests?

I have heard anecdotally that some people propose plotting interactions and interpreting the plots, rather than conducting follow up tests. Is this an acceptable approach? Is there a good reference to ...
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0answers
34 views

Interpreting the coefficient of the interaction between 2 (binary) endogenous variables

I have the following outcome (second-stage) equation: $$y = \beta_0 + \beta_1w + \beta_2x + \beta_3w x + \cdots$$ $y$, $w$ and $x$ are all binary. Both $w$ and $x$ are endogenous, but I have an ...
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16 views

What is the best way to plot an interaction, that accounts for other control variables?

Imagine that I'm interested in seeing if there is an interaction between hair colour and weight, as predictors of a person's speed, after accounting for height. How can I plot this interaction in a ...
2
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1answer
61 views

Do interaction terms in a linear regression model increase its predictive power?

Interaction terms are sometimes added to linear regression models when the effect of one variable depends on the value of another variable. But will the inclusion of such interaction terms increase ...
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0answers
20 views

How to interpret the interaction between multicategory categorical variables? [duplicate]

My outcome of interest is "disease or non disease". I have two categorical variables A (age group in years- 1-5, 5.1-10, 10.1-15, 15.1-19) and B (place of residence- Ba, Bb, Bc). I have fitted ...
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1answer
39 views

significant Interaction between a significant discrete variable and non significant continuous variable

In my dataset, I have to test the effect of humidity on the height of plants. However, we have an extra effect which is nitrate on height. Each plant had a nitrate measurement but we had one group in "...
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1answer
16 views

Possible to have main effects and interaction in 2-way ANOVA?

In a 2 way ANOVA, can you have a significant main effect for each IV and an interaction? Why should caution be used when interpreting main effects if you have an interaction?
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1answer
104 views

Resampling-based Confidence Intervals for RERI

Relative Excess Risk Due to Interaction (RERI) has been used to quantify the joint effects of 2 exposures in epidemiology. RERI is the proportion of disease among those with both exposures that is ...
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1answer
34 views

Regression with interaction, interpretating main effect

I have a question regarding testing interaction terms in regression. When we have significant interaction term, do we still interpret main effects? I have made two models, one with interaction term ...
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1answer
44 views

Can you “reverse” an interaction plot and still interpret it?

I am interested in studying the interaction with a ordinal predictor p and continuous moderator m on an outcome y with a simple model of: y ~ p + m + p*m However, since my predictor is categorical, ...
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1answer
43 views

If A causes B & A causes C, can B modify the effect of A on C?

Suppose I roll out an initiative to promote a new vaccine in a country, call this intervention A. A causes uptake of vaccines C, but it may or may not also cause backlash from community leaders ...
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2answers
409 views

In linear regression, why should we include quadratic terms when we are only interested in interaction terms?

Suppose I am interested in a linear regression model, for $$Y_i = \beta_0 + \beta_1x_1 + \beta_2x_2 + \beta_3x_1x_2$$, because I would like to see if an interaction between the two covariates have an ...
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2answers
51 views

Regression: Interactions terms of factors with several levels (interpretation)

I'm running the following linear model in R: lm(formula = Valence ~ StatusOfMandarin * Condition, data = d_afraid, na.action = na.omit) My data is as follow ...
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147 views

Interaction in fractional polynomial regression in R using the mfp package

I am modelling the relationship between waist circumference and triglycerides using fractional polynomials and the mfp package in R. I want to assess whether this relationship differs for ethnic ...