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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28 views

How do I interpret a significant three-way interaction when all two-way interactions are not significant? [duplicate]

How do I interpret a three-way interaction when all two-way interactions are not significant?
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187 views

Calculate interaction effect confidence intervals in zero-inflated poisson regression

I'm conducting a zero-inflated Poisson regression using the pscl package in R. I've included interaction terms but am having an issue with interpretation. I am assuming an additive effect and summing ...
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107 views

multiple logistic regressions with binary predictors vs single logistic regression with categorical predictors

I would like to know which is statistically more advisable and what are the advantages and disadvantages of each approach. My data frame data has ...
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42 views

Independent variables and moderator variables correlate (three-way interaction)

let's assume I hypothesize: H1: A direct effect of X1 on Y H2: A direct effect of X2 on Y H3: A two-way interaction between X1 and X2 H4: A three-way interaction between X1, X2 and X3 H5: A three-...
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1answer
52 views

Effect Modification, Confounding, and Correlation

I am trying to estimate the effect of a policy intervention (X) on patient outcome(Y) from an administrative data. In the data set, around 20% of the patients have received the intervention. Even ...
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110 views

interaction with a mixed logistic regression using mlogit on choice data

What is the best way to analyse interactions in choice data between an individual specific variable and an alternative specific variable? I have designed a discrete choice experiment in which ...
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56 views

Interpretation of interaction terms

I try to improve my statistical knowledge and right now I am working on a regression that contains interaction terms. I am currently investigating the effects of different variables ($a_1$, $a_2$ etc.)...
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Obtaining the fitted values of main effects and interactions when GLM coding is used

In short, I need to decompose the fitted values obtained from ANOVA into components corresponding to each term in ANOVA statement. This problem appears trivial, but it becomes tricky when GLM coding ...
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Comparing two difference-in-difference models when making the treatment group larger

I have a question regarding some potentially existing empirical tests in the difference-in-difference context. Assume that I have the usual setting of observing some hypothetical outcome for a ...
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Method for testing interaction in regression analysis

I am running a linear model with 6 explanatory variables (5 in classes, 1 quantitative), and would like to test which interaction(s) are eventually significant. I think an ascendant stepwise method ...
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22 views

testing specific effects from a significant interaction in mixed models

Let's say I have this model ...
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regression analysis assessing the relationship between brain volume and behavioural score, main effect but what to do with the moderating variable?

I am conducting a regression analysis to look at the relationship between a behavioural score and brain volume. My sample is made of 2 patient groups: A and B. The model includes the following ...
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1answer
47 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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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
286 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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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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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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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
46 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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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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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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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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21 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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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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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
49 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
47 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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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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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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234 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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84 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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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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56 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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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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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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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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41 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
24 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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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
42 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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139 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
295 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
92 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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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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24 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
61 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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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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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 ...