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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.

2
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1answer
29 views

When non-significant interaction effects make a significant main effect non-significant [duplicate]

Suppose that I have two IVs (AnxietyLevel & experimental conditions (dummy coded as 0 and 1), and two control variables (Age & Gender) and one DV (mean score on a questionnaire). And I am ...
2
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1answer
138 views

How to include an interaction with a quadratic term? [on hold]

I want to predict $y$ with $x_{1}$ and $x_{2}$ and I suppose that $x_{2}$ has a quadratic effect on $y$ and that there is an interaction. How to model that? I've look in previous questions but there ...
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0answers
15 views

simr power simulation testing interaction term for 2 factors

I have a model with two factors: a (4 levels) and b (3 levels). Each participant receives two problems (id as a random effect). I want to estimate sample size based on pilot data to give me ...
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0answers
28 views

Interaction significant, simple effects not

I'm running a regression which showed a significant interaction effect between my variable design (0,1) and device (0,1) on view time. However, i did not found a main effect of design on view time. ...
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0answers
13 views

interaction effect multifactor nested design for non-paired data

stackexchange, I am interested in the difference of the treatment effect in healthy vs diseased donors (treatment:group), but need to control for high donor variability. Figure 1 As can be seen in ...
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0answers
9 views

Simple slopes analysis for regression with user defined contrast codes [on hold]

I am struggling with conducting a linear regression with user defined contrast codes and simple slope analyses of significant interactions between the contrast codes and categorical and continuous ...
0
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0answers
26 views

Longitudinal mixed-model with co-varaites

I'm currently have a longitudinal dataset with dependent variable Y measures over two time points (variable = Time) across 4 groups (variable = Group). This variable Y is a continuous variable ...
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1answer
454 views

How to interpret interaction between categorical and continuous variable?

I have a question regarding the analysis/interpretation of a significant interaction between a continuous variable and a categorical variable, which seems pretty easy but I just don't understand it ...
0
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1answer
334 views

Interaction terms in cross-sectional regression

I have a question regarding the use of interaction terms in a cross-sectional regression model. Currently I am working on a study for which I have a sample consisting of roughly 500 observations, ...
3
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1answer
482 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 ...
0
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1answer
25 views

How do you use panel data to isolate the relationship of interest for a particular individual within your panel?

I have a panel data set where Canadian provinces are the individuals. (I have annual data from 1997-2017). I am using a random effects model to see the impact of an explanatory variable $X_{it}$ on ...
4
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1answer
372 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 ...
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0answers
21 views

Integrals simulation in the program R [closed]

Given the simulation with the R program, show that the integral is below $\int_0^{\sigma^\pi (x)} x^2 \lambda e^{-\lambda x} d x =1/2$ . Assumptions of the problem let $x|\lambda \sim exp (\lambda) \...
1
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1answer
39 views

help interpret interaction effect in linear mixed effect

I am trying to predict response time (transformed in Log) from Group (a factor with two levels: NS and NNS), and Time of Testing (a factor with three levels: Pretest, Posttest, Delayed-test), using ...
0
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1answer
27 views

Interpret contradicting output of lmer model with categorical interaction in R

I am struggling to interpret my output in R. It does not make sense to me. I first regressed participants' ratings (= value) on manipulations (...
0
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2answers
29 views

Bayes factors and predictive accuracy in model comparison in rstan / brms

Despite reading up on the subject, I can't wrap my head round it, so the question remains on shaky grounds, and responses along the lines of "read chapter x" are very welcome. What I'm doing is I'm ...
4
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1answer
28 views

How powerful are second order interactions?

A lot of applications in statistics and machine learning model a phenomenon by second order interactions of variables and get good results. By second order interactions I mean, for a general variable $...
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0answers
54 views

Calculate odds ratios and P-value for interaction across multiple separate subgroups

I'm trying to understand/replicate an adjusted logistic regression analysis where a treatment effect is estimated separately in a number (>2) of subgroups and estimating an overall P-value for ...
1
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1answer
182 views

glm.nb with interactions - interpretation

My data was over-dispersed (dispersion coefficient over 5), so i have fitted negative binomial model. ...
1
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1answer
179 views

interpretation of interaction-term in linear regression, with and without main-effect

In a case-control study including men and women of various ages, I wish to investigate if there is a difference in a measured variable (X) between cases and ...
0
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0answers
14 views

similar risk estimates between groups but have significant interaction

I am running a cox proportional hazard model to analyze the association between air pollution and risk of mortality. In the subgroup analysis, I obtained some confusing results. For example, when ...
4
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1answer
2k views

Pairwise comparisons with emmeans for a mixed three-way interaction in a linear mixed-effects model

I have a rookie question about emmeans in R. I fit a complex model using lmer() with the following variables: A: a binary categorical predictor, within-subject B: a binary categorical predictor, ...
0
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1answer
23 views

Modeling interaction in variance

I run an experiment on both men and women participants, where I manipulate an independent variable. I know that the manipulation causes greater variance in the outcomes of the experimental group (a ...
1
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1answer
17 views

Visualize cross over interaction logistic regression categorical variable in R

I have performed a logistic regression with the following variables: X: Categorical with three levels (St, An, Int) M: Moderator, which has two levels (Mob,Desk) Y: Dichotomous dependent variable (0/...
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0answers
36 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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0answers
14 views

ANCOVA: resolving hetrogeneity of regression slopes with multilevel modelling vs adding an interaction term

On the Wikipedia page for Multilevel model it is written that [M]ultilevel models can be used as an alternative to ANCOVA, where scores on the dependent variable are adjusted for covariates (e.g....
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0answers
14 views

Estimating weights in the assignment problem

How would you learn a function with the emphasis on feature interactions? I have the standard assignment problem: $$ \max_{x_{ij}} \sum_{(i, j)} w_{ij} x_{ij}, $$ where $w_{ij}$ is the weight of ...
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0answers
28 views

Testing interaction terms individually and simultaneously

I am currently testing two interaction terms individually in OLS regressions. Both interaction terms are significant (p < .5) when tested individually (i.e., two regression equations, one for each ...
2
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0answers
48 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 ...
0
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1answer
78 views

Help in Two-way ANOVA with Significant Interaction

(note: I removed the original table because there were some mistakes in it. I preferred to use R annotation of Sal's answer.) Hi everybody, I got the following results for an experiment of ...
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0answers
12 views

non homogonous data and interaction

I have an experiment design with: Variable 1 - 2 levels Variable 2 - 3 levels And demographic information collected about my participants: Demographic 1 - 2 levels Demographic 2 - 3 levels ...
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0answers
18 views

Multiple linear regression with dependent as a dummy predictor

I have a model $Y = \alpha + \beta_1X_1 + \beta_2X_2$. $Y$ has a bimodal normal(ish) distribution, so I'm looking to see if the relationship between the predictors and the response is different for ...
0
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1answer
182 views

Testing the significance of a main effect using model comparison, when an interaction is included

I am fitting a linear mixed effect model (using lmer), and want to obtain p-values via model comparison. As far as I understand it, the procedure is: (i) create a ...
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0answers
16 views

Logit model: Interpretation of interaction effect with only dummies

I have a large binary logit model (cross-section) with many variables, mostly dummies. From the information on age, I have created 6 dummies: 17-24, 25-34, 35-44, 45-54 (reference group), 55-64 and 65+...
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3answers
116 views

Interaction between dependent and independent variable

I am conducting a multiple linear regression on data from a cross-sectional study, and I suspect that there is an interaction between my dependent variable (a disease risk marker) and one independent ...
1
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1answer
450 views

Why no interaction in two-way ANOVA without replication

This may seem like a silly question, but I can't figure out (or find anywhere) why it's not possible to calculate interaction with a 2-way ANOVA without replication? Has it something to do with the d....
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0answers
9 views

How to properly represent a sum of interactions in ANOVA?

I would like to include an ANOVA-style linear model in my work that shows the main effects but has interactions lumped together in one term for brevity. When I do the analysis I will include the ...
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0answers
5k views

What do the tests of model effects and parameter estimates really tell (when an interaction is defined)?

A couple of times in LMM or GEE (with SPSS, though I doubt that matters – and might occur in other analyses as well, but these are the ones with which I have seen it) I have seen something that seems ...
1
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1answer
526 views

Panel regression / use of dummies as interaction terms

I am interested in using a fixed effects panel regression for my research question. Using fixed effects model instead of random effects is dictated by the Hausmann test results. In my sample, I have ...
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0answers
8 views

Interaction in logit

I am estimating a model where interaction terms play a role, and I am wondering which specification I should use, and how to interpret the results. More specifically, I regress a binary variable, say ...
1
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1answer
27 views

Interaction term to deal with heteroscedasticity

The variance in my dependent variable changes with a changing value in an important independent variable and is hence probably distorting the measured effect of the treatment. Can I combat this form ...
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0answers
15 views

Interpreting models with omitted interaction effects

Suppose I have two regressors, task availability (Xa) and task participation (Xp), and a DV Y. One can only participate in a task if it is available, but one can choose not to participate even if a ...
1
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1answer
33 views

How to interpret interaction in Log Log models

I have the following model, and I am not sure how to interpret the elasticity of the interaction term (log-log coefficients): Log(member) = 3.61 + 0.52 Log(Poor) - 0.26 Log(Sick) + 0.04 (Log(poor) * ...
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2answers
562 views

Interaction terms in level-log regression

I have the following regression: $y=\alpha + \beta_{1}\text{ln}x_{1} + \beta_{2}(\text{ln} x_{1}\cdot \text{ln}x_{2})$ How do I interpret the marginal effect of $x_{1}$ on $y$? I haven't find anything ...
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1answer
403 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.) ...
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0answers
9 views

Mediation model of time series data

I'm quite new to mediation analysis so hopefully I can clearly explain my problem. I wish to conduct a mediation model with a single mediating variable. The independent variable is a time series EEG ...
0
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1answer
24 views

Interpretation linear mixed model with interaction

I'm doing linear mixed model with an interaction between the time and my exposure. The fixed effects look like this : Y ~ T + T*GRP + X with T the time, GRP the exposure and X the adjustements ...
8
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2answers
220 views

Different ways of modelling interactions between continuous and categorical predictors in GAM

The following question builds on the discussion found on this page. Given a response variable y, a continuous explanatory variable ...
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0answers
10 views

Testing moderation hypothesis in regression discontinuity analysis

I am doing a regression discontinuity analysis in R (using the rdd package) and I am interested in testing a moderation hypothesis. I think that the effect of the treatment will depend on a third ...
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0answers
4 views

Using random forest to generate interaction terms for linear regression

What I want to do is: Setting random forest's each tree to be very shallow, probably 2 levels, or 3. Then I will create 100 trees. After that, I will use each tree's result as a predictor, and then ...