# 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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### Why is the format of the F-values in my type III ANOVA output different? [closed]

I am looking at how factors A, B and C interact to influence the duration of the continuous variable X using a type-III ANOVA analysis using the following code: ...
12 views

### 3 way interaction, residual plot showing clustering across fitted values, do I need to account for grouping in a different way?

I have created a model with a three way interaction, analyzing how taste of bread (fr2) decreases over time (time2), and how skill of the baker (skill2) impacts longevity of taste, across different ...
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1 vote
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### Need help interpreting interaction effects

I have two categorical independent variables (Category: Before/After and Treatment [A,B,C]) and a binary response. My regression output in R is as follows: ...
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### Omit continuous variable in categorical by continuous interaction

I'm trying to understand whether excluding the main effect of income in this specification is valid. Gender is a 0/1 variable whether the individual is male/female. Income and NetWorth are continuous. ...
1 vote
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### can add of interaction term makes a third term insignificant?

I was reading a paper. There are 3 regression: the baseline regression: financial development of city i on city level deposit amount, control for road density, and the coefficient on road density is ...
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### Centering two level-1 variables to create interaction term before multilevel analyses? Thank you [duplicate]

I like to ask for some kind help from the readers here. I have a specific question on creating the interaction term from two level-1 variables before even running the multilevel analyses. Do you mean-...
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### Can you use a MANCOVA with a DV measured twice and a DV measured once? [closed]

Can you use a MANCOVA with a 4 level IV, a covariate measured once, a within-subject factor (Time) relating to a DV measured twice, and another DV just measured once? I want to see: Is there a ...
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### Can you assess Moderation with ANCOVA?

I am using SPSS for analysis with 1 group IV (4 levels), one DV measured at time 1 and time 2 for each participant in each group, and one covariate measured once at time 2 or for each participant in ...
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1 vote
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### Subgroup analyses after propensity score matching

Assume an already propensity score matched cohort. One of the variables included in the propensity score model is sex. The main cox model investigates the comparative effect of two drugs for cancer ...
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### How do you model the two-way interactions between a continuous variable and two factors but not the three-way interaction with GAMs?

For the example, let's suppose I'm trying to model the level of activity of some frogs depending on a continuous variable (water temperature) and two factors : their sex (M or F) and the period of the ...
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### Can I model the interaction between a continuous variable and two factors separately for each factor?

I'm wondering if I can model the effect of the interaction between a continuous variable and two factors in a model without including the three-way interaction between the two factors. Let's imagine I ...
1 vote
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### ANCOVA or MODERATION?

I'm struggling with the statistics for a question I'm collecting data to answer. My paper is about whether different meditation types can increase happiness when controlling for meaning in life. There ...
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### Plotting interaction by logistic regression

I have used R to plot the interaction term from the logit function I computed. I use the standard cat_plot() to plot the interaction. I clearly see that the two ...
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### Should I expect statistical analytical problems in this PLS-SEM structure?

Dear all great statisticians ... I am a doctoral student and my conceptual framework contains five variables. Among these variables are a mediator and a moderator. I am not sure of the validity of ...
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### In a 2 arm pre-post RCT, is an interaction test on an ANOVA the same as a t-test of the change scores?

Say you have a 2-armed pre-test post-test control trial design. You want to test the effect of group allocation on the outcome variable. I simulated a version of this in R, using 3 different methods: ...
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### How to establish a predictive model for implementing or not implementing checks as an exposure factor?

I have observational data on a prospective cohort, including baseline measurements such as blood pressure and glucose, as well as data on cardiovascular disease incidence with 10-year follow-up. I ...
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### How to interpret results of a GLM from a double factor experimental design

I have an experiment with two factors "Enzyme", and "FeedMixture" which has 4 different levels. "FeedMixture", is a variable of type factor. Below I simulate a response ...
1 vote
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### Calculate Levene test in R

I'm trying to calculate the Levene tests with multiple interactions. ...
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### Whats the correct way to nest for VCA (Day, Lot, Operatore)?

I have a data set for a study im working on, i'm usually pretty good with stats but the more I look at this the more I question myself. So I have a measurement of a analyte taken by two different ...
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### How does a logistic ordinal regression model learn the interaction between the features?

I have a dataset of informations about students and the last column is the target variable which is the final note. My goal is to make logistic regression and ordinal regression models to see whether ...
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### Is including all pair-wise interactions in a three-way interaction linear regression model necessary?

I am trying to assess the impact of X on Y with Z as a control and a dummy variable (D), which takes a value of 0/1. However, to test my hypothesis, I have interacted with XZD as I want to see the ...
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### How can it be that the moderation analisys is not significant but at +- 1 sd of the simple slope analysis all slopes are?

I'm currently working on some preliminary data (185 subjects). I'm using moderation analysis with jamovi medmod package, 10000 bootstraps, continuous calculated variables (mean of items from a survey)....
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1 vote
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### Interpretation of generalized linear mixed-effects models: How should I proceed with a significant interaction term?

My experiment has the following factors: "year" (fixed) with levels "1" and "2" "age" (fixed) with levels "old" and "new" "treatment&...
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### Detecting interactions in large logistic regression models

I have a dataset of a few million observations of a binary response with a low "Success"-probability of on average 1% to 2%. The dataset encompasses several categorical (~20 some with up to ...
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### What exactely is "the part of the interaction orthogonal to factors $A$ and $B$" in a two-way ANOVA?

Consider a two-way ANOVA with factors $A$ and $B$ and the interaction $A\times B$. The author of this answer answer https://stats.stackexchange.com/a/608301/359647 (@svendvn) explains that the Type ...
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1 vote
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### Does a significant interaction & effect imply an effect in both groups? [duplicate]

I'm fitting an interaction model for two treatment groups: water and saline. Participants of the study, at different ages $X$, begin the treatment and $Y$ is measured. I fit an interaction model Y = ...
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### Confidence intervals around treatment effect in stratified experiment

Suppose you conduct an experiment, where a population is randomized and treatment is given to the treatment group and you are interested in covariates (stratification has been employed) and their ...
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### Relationship between f test and t -test [duplicate]

I am working on a problem where I should derive the t test statistic from an f test given an ANOVA table (below). From my understanding, when we conduct an f-test we are using the variance to ...
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### Linear mixed models with and without interactions

Here is the context: I asked two types of questions 8 times (8 "sessions" with 2 questions, each question has a "number" i.e. whether it is the first or second question asked, and ...
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### Mathematical formula for interaction term in multiple regression with two predictors [duplicate]

I am trying to understand the math behind the coefficients in a multiple regression with two predictors and their interaction. I know that this can be done in matrix notation OR directly in any ...
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### Modeling longitudinal change in outcome per unit of change in a continuous explanatory variable

My question is related to How do you deal with "nested" variables in a regression model? However, my issue is slightly different. I'm analyzing RNA-seq gene expression data (>10 000 genes)...
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### Is an interaction term essentially interpreted as just another independent variable?

I'm trying to understand if the linear regression model interprets an interaction term as just another independent variable? This is the formula for linear regression with 2 independent variables ...
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### Mixed models - interactions or individual regression

I am using LMMs and GLMMs(where necessary) to model carbon pools between different treatments. i.e specifically intrested in contrasts. These pools are divided between different groups e.g. diferent ...
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### Should I run a moderated regression or a regression on a subset of my data?

My hypothesis is that my iv predicts my dv only among people who have a PhD. I have seen two ways to test this hypothesis: Run a regression with a moderation between my iv and the education variable ...
1 vote
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### Comparing two models from the "fish" dataset

Data I'm constructing linear models using the fish dataset from this data with the following variables: res_var: response ...
1 vote
175 views

### Can raw means and estimated marginal means be the same ? And when?

I have read a lot about calculating raw (standard) means and EMM. First are data based (descriptive stats), the latter are model based. I try to learn how to calculate both of them. In my example both ...
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### Missing predictor variable in GLMM.nb outcome

After running the model: ...
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### nlme prediction differs largely from a 3 way interaction model to its post-hoc follow up

I'm trying to predict that speed at which people complete a walking test, where they perform this test for multiple trials and overall increase their performance on each trial. They perform as many ...
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### Interpreting interaction coefficients between continuous and categorical variables + interaction plot with confidence bands

I ran a between-subjects experiment in which 114 people evaluated 1 innovative idea, and I manipulated the source of the idea (IV1 = source; categorical: internal vs. external) to see if it affected ...
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### Regression with depended predictors, animal study sample size [closed]

I have a few questions for help, One of my predictors is for treatment and control. Another predictor is dosage. Treatment group has 4 dose levels which control group only has one. Can I still use ...
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### Beta regression for interaction terms without full rank? (R)

I have a series of beta regressions I have performed on the effects of tissue type, year, and age class on the eccentricity of ellipses, which varies between 0 and 1. I have created interaction models ...
1 vote
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### How does type II vs type III ANOVA work when there are more than two categorical predictors?

For a model with two categorical factors in the form: X = A + B Type I (used if the factors are balanced) calculates SS for each term in the model sequentially as follows: SS(A) then SS(B|A) = SS(A ...
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### Interaction term vs subgroup analysis

I have a question regarding the choice between interaction term and subgroup analysis. Suppose that I want to study the association between education and income by sex. I can fit a model with an ...
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### moderated mediation vs mediated moderation

I am looking for a detailed explanation of moderated mediation and mediated moderation. My basic understanding is that in moderated mediation, we have a classical mediation model with the addition of ...
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### Cox regression with two-way interaction and interaction p value

Hi I am using Cox regression to do some survival analysis. I have one continous predictor variable called "biomarker" and two binary categorical variables sex and diabetes. I want to get the ...
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### Which of these is the correct way to encode a type III ANOVA analysis?

I am trying to run a type III ANOVA analysis to look at how the three factors A, B and C affect the continuous variable X. Online I have found two ways of encoding the model which give different ...
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### Am I using emmeans correctly to look at pairwise differences after running a type III ANOVA model?

I am looking at how the weight of female individuals is influenced by the two factors A (5 levels) and B (2 levels) using a type III ANOVA as follows: ...
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### Comparing Hierarchical regression models from the same sample

I'm running a survey where I'd like to compare three models with the same set of variables except for the moderator. I'm looking for the strongest interaction effects as a foundation for subsequent ...
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