# Questions tagged [interaction]

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

616 questions with no upvoted or accepted answers
Filter by
Sorted by
Tagged with
1answer
1k views

### Ratios in Regression, aka Questions on Kronmal

Recently, randomly browsing questions triggered a memory of on off-hand comment from one of my professors a few years back warning about the usage of ratios in regression models. So I started reading ...
0answers
5k views

### Panel regressions with an interaction term between a time dummy variable and a time invariant variable

I have estimated the coefficients of the following equation, using the fixed-effect model: $Y_{it}=\alpha _i+ \rho _t + \beta _1 X_{it}+\beta _2 C_i*D_t+\epsilon_{it}$ I have observations from 1980 ...
0answers
2k views

### Interpretation of crossed random effect interactions in lme4

I'm considering a model in lme4 in which I am estimating random effects for two crossed factors, very similar to the Machines example in Bates' 2010 draft book (http://lme4.r-forge.r-project.org/lMMwR/...
0answers
556 views

### When and How to Scale Numeric Interaction Variables in Machine Learning Model

I found one similar question on cross validated, but it was unanswered; my apologies if this has been answered. I'm experimenting with feature interaction in a regression model I'm working on in R. ...
1answer
414 views

### testing for mediation of interactions

I am somewhat familiar with various ways of testing mediation for factors in different types of regression analysis. (I'm using R and currently working with a multilevel binary logistic regression.) ...
0answers
74 views

### Interaction plot between categorical and quadratic continuous variable

I ran a GLMM model with a binomial response to analyse bear presence at feeding sites (0 = absent, 1 = present) within two years. My code is: ...
0answers
111 views

### A few questions regarding the practice of heterogeneous treatment effect analysis (a.k.a, interaction detection or subgroup analysis) methods

Imagine I am looking at a randomized experiment between a control and one or more treatment conditions. For example, I have a treatment that aims to get people out of debt. I randomize people to ...
0answers
102 views

### Cox interactions and co-linearity

I am interested in developing a model to predict survival based on a few predictors: age, sex, and two lab values, albumin and globulin. I have approximately 14,000 deaths in the data. I initially ...
1answer
407 views

### Poisson regression on aggregated data with an interaction term

For me, Poisson regression has been a nice tool to estimate risk ratios (setting offset to log-number of group size) and rate ratios (setting offset to log-risktime). Recently I came across a ...
1answer
158 views

### Can a decision tree automatically detect the effect on the dependent variable from the product/quotient of two independent variables?

For example, when I use the xgboost algorithm, there are two continuous variables X1 and X2, do I need to specify the product X1*X2 explicitly at the beginning? Or the algorithm can automatically pick ...
0answers
88 views

### Testing differences between slopes by examining proportions rather than interactions

In a recent article published in Nature Genetics, Francioli et al. argue that the relationship between paternal age and mutation rate depends on what part of the genome you're looking at (intergenic ...
0answers
354 views

### When including a linear interaction between two continuous predictors, should one generally also include quadratic predictors?

Suppose I am fitting a linear model, and I have two continuous predictors x1 and x2. I think that they might interact, so I add ...
0answers
897 views

### How to write a mathematical equation for GLM model with gamma and gaussian distribution?

I am writing a paper and the following is a code that I wrote in R. The reason that I am struggling with this is because I tried hundreds of models with different variables and the following model ...
0answers
612 views

### How to quantify moderation effect in an intervention study with multiple time points?

I want to measure a moderation effect between 3 continuous variable in an intervention study. I am using scores from self-report measures of masculinity, emotionality, and psychological distress. The ...
0answers
38 views

### If parallel trends assumption is not met for diff-in-diff analysis, why not add more interaction terms to regression model?

The literature presents a violation of the parallel trends assumption as a major obstacle when performing a difference-in-differences analysis. Why can't we model non-parallel trends by simply ...
0answers
62 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 ...
0answers
65 views

### Forms of interaction between variables Random Forests take into account

What forms of interaction do Random Forests take into account? I understand from other posts ( Including Interaction Terms in Random Forest ) that Random Forests take into account interactions like x1 ...
0answers
27 views

### Incorporating Measurements of Item Uncertainty into Bayesian Models

Imagine I have a dataset of four variables: Age (Continuous) Gender (M/F) Vote for Incumbent (Yes/No) Like Leader (Yes/No) However, I also have two additional pieces of paradata: how long it took ...
0answers
78 views

### Could interaction effects prevent GLMM's (lme4) from converging?

In the following analysis, I am exploring the association between health outcomes and a range of environmental and socioeconomic predictors. These data have been collected from 9 countries, over ...
0answers
57 views

### Framework for simulating SEM data w/ moderation + mediation, testing models

I'm interested in extrapolating treatment effects from RCTs to new populations under conditions where populations exhibit relevant differences that induce differences in treatment effects. My aim is ...
0answers
277 views

### Interaction effect in random forest

I'm interested in interaction effect between variables in random forest. I found some information here https://www.stat.berkeley.edu/~breiman/RandomForests/cc_home.htm#workings. The operating ...
1answer
556 views

### Plotting smoothed hazard ratio intervals for interaction terms

I don't know if it is possible. I am following Terry Therneau's Spline terms in a Cox model vignette available for survival package. In Section 3, Splines in an ...
0answers
236 views

### Can a random slope be interpreted similarly to interaction effects in longitudinal analysis?

I am modeling wheat yields over time at several locations using mixed models in R (lmer function). My selected model is as follows: ...
2answers
149 views

### Probabilty Scale Versus Log Odds - Interaction Effect Size

I am looking at doing some power analysis for a simple full factorial design using logistic regression as the method of analysis 2 main effects and their interaction. I am trying to discern the ...
0answers
886 views

### Interaction terms in multinomial logit regression

I'm analyzing the relationship between women's BMI status (underweight, normal, overweight) and five predictors ( their wealth, their education, the region where they live, their score of dietary ...
0answers
132 views

### What is the difference between bi-level linear models and models with interaction terms?

My question is triggered by this question. I can't see that it has been asked here before, even though it looks like a natural enough question. Suppose I have hierarchical data. The Wikipedia article ...
0answers
489 views

### How to check variables changeable dependency in R?

I would be very thankful if somebody could help me and explain the answer in simple terms. I have y, x, z variables. They are countinuous, no missing values. y is dependent variable, x and z ...
0answers
303 views

### How does the presence of factors affect the interpretation of the other coefficients in a regression?

The answer to Interpreting coefficients of an interaction between categorical and continuous variable contains a phrase that seems to have some significant impact on how coefficients are interpreted ...
0answers
3k views

### How to determine the significance of an interaction?

My question is simple: How do you determine the overall significance of an interaction (i.e. the marginal effect of $X$ on $Y$ for different values of $Z$)? But the background is a bit long-winded,...
0answers
102 views

### Which statistical test for women height?

Suppose women may have Blue or Red eyes. We make a first cheap research on a 100 women checking just one eye of each woman. So after the research we have results: At least one eye Blue have avg ...
0answers
201 views

### Contradicting interaction significance with graphical visualisation in glmer

I'm investigating environmental effects (wind) on acoustic receiver detection probability for two types of transmitters using a binomial glmer. While my model analysis indicates that there's a ...
0answers
265 views

### Estimating a confidence interval around the average of an interacted treatment effect

I've got a causal inference situation with heterogeneous treatment effects. In addition to simply estimating coefficients, I'd like to get an average effect of the treatment at the covariate values ...
0answers
228 views

### Standard error computation with interaction term

I aimed at studying the effects of an exposure (E) on fetal growth estimated by repeated ultrasound measurements (n = 2 measures per participant in the following example). I used interaction terms of ...
0answers
175 views

### Effect of Age-Period-Cohort on prediction and interactions

I am performing a longitudinal analysis and I am curious if the predictors we are including in the model will introduce any unexpected effects. We have subjects with multiple points of follow-up ...
0answers
2k views

### How to interpret chi-squared test for main effect in presence of interaction term

I have run a sequence of nested multi-level models using lmer, and looked at both the summary output giving all the coefficients, etc, as well as the Anova output which does a chi-squared test on each ...
0answers
1k views

### Power analysis for moderator effect and mediation analysis

I want to do an a priori analysis of minimum sample size with G*Power and I have two questions about this: First, I will test an interaction effect for a moderator variable. I am not sure which ...
0answers
101 views

### How to deal with kurtotic interaction variable?

I'm going to do a multiple regression analysis with two continuous IVs and their interaction. I've centered the IVs and then multiplied one with another for interaction. My problem is that the ...
0answers
659 views

### Interpretation of interaction term in Cox PH model when centering LP on mean values of predictors

Let's say I have a Cox PH model for predicting the risk of dying, that in a simplified form looks something like this: ...
0answers
365 views

### Fractional Polynomial interpreting interaction terms

Background: I have developed a logistic regression model where I am trying to analyze the effect of socio-economic data of a family on their probability of receiving a home loan. I have used ...
0answers
237 views

### Algorithm for selecting interactions without very many degrees of freedom (mgcv, gam)

I've got a semi-parametric model that I'm fitting with GAM's (mgcv in R). It is of the form $$y = \theta + X'\beta + f(Z) + \text{Interactions!} + \epsilon$$ I've got 289 observations. Many of ...
0answers
235 views

### Repeated measures interaction betwen SNP and treatment with R

This is my first question is this forum. I have the a problem that I want to solve with the lme function of the nlme package of <...
0answers
759 views

### Unfold degrees of freedom of interaction in factorial design analysis in R

I've been trying to analyse data from a factorial design with missing cells without much success until now. I'm using Anova from car package, that, according with I've read, can handle unbalanced data ...
0answers
373 views

### Binary interaction terms using lmer

I am trying to create a model using the lmer function. The model will contain the continuous response term "Average.profit" and explanatory terms "Type", "OtherType,...
0answers
16 views

### How to compute and interpret interaction term between continuous variables that have negative values?

I was wondering about the computation and interpretation of interaction terms of continuous variables that are used in a multiple regression. Normally, one would mean-center (or z-standardize) the two ...
0answers
51 views

### Using a t-test to follow-up on a non-significant interaction in an ANCOVA?

My question is about whether a t-test can be used to follow-up on a non-significant interaction found with an ANCOVA. I have an experiment that compares the impacts on students' learning (as measured ...
0answers
136 views

### Interpreting interaction term on highly correlated variables

Somebody at a meeting today made the following comment about a Marketing Mix Model (Linear Regression) we run every year. We should account for the high collinearity of the two Marketing Variables (...
1answer
27 views

### Interaction term and sample selection

I have a dependent variable Y which is continuous. I want to study the impact of X on Y using OLS in a linear model, but I suspect the impact of X is more important for observations with a high value ...
0answers
13 views

### 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 ...
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 ...
0answers
48 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 ...