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

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How to chose covariates to adjust for in a regression analysis

I am running a regression analysis where my primary interest is to see if the outcome differs by the group (treatment vs. control). However, I have some 80 other clinical and socio-demographic ...
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26 views

What is the b statistic reported in a t-test?

For more context, this is what was reported in the article .. "In support of our hypothesis, we found a significant three-way interaction for [..the dependent variable..] (b =.22, SE = .10, t(417) = 2....
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1answer
32 views

3-way ANOVA with a significant 2-way interaction. What are my next steps?

I have performed a mixed 3 way ANOVA: Group (2 levels) x Factor2 (2 levels) x Factor3 (2 levels). There was no significant 3-way interaction; however, there was a significant 2-way interaction ...
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25 views

perfect separation after adding interaction term

I am using glm to estimate a model (dependent is dummy). I have two continuous variables that I want to test their interaction. As soon as I add the interaction ...
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0answers
16 views

TukeyHSD for the interaction term after mixed ANOVA

I have recently run a 2 (between variable: native, non-native) x 3 (offer: £1, £2.5, £4) mixed-design ANOVA with repeated measures on offer type. I got a significant result for offer type and the ...
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9 views

Type-I error adjustment for simple effects when 2x3 factorial ANOVA interaction only is significant

I have found several questions and answers that skirt around my problem but I haven't been able to deduce a clear solution. My situation is this: I ran an experiment with a 2x3 factorial design (call ...
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0answers
12 views

Testing if a correlation between two ordinal variables depends on a third variable

I have two ordinal variables : $y_1$ (a dummy) and $y_2$ (five categories). I know they are correlated, but I have reasons to believe this correlation depends on a third variable ($z$). An interaction ...
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13 views

Test significance of combined interaction coefficients

Is there a way to test the significance of combined (interaction) coefficients in R? I have a panel regression model of the following (simplified) form: yi,t = b0 + b1xi,t + b2xi,t*phase_1t+ b3xi,...
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17 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 ...
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0answers
11 views

Sample size assessment for two-way ANOVA with repeated measures with GPOWER (or other software?)

I’m trying to assess the sample size for the interaction of two within subjects factors, in a two-way ANOVA with repeated measures design. Design: In a single sample, participants; On the first week ...
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0answers
36 views

Do I need to include interaction in the model when I am only interested in overall effect? [closed]

Say I am doing a linear model, with treatment and study effects, and I know the treatment effects are different across studies. I want to estimate the OVERALL treatment effect (NOT study-specific ...
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33 views

Stratifying after significant interaction to understand within group associations

I am working on a an analyses that includes an interaction between a categorical variable and a continuous variable. It is a GLM with a binomial(logit) link function. The interaction is between ...
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0answers
6 views

GEE model issues and interaction interpretation

I am doing my first data analysis and I am confused with some results - let me know if you need any more information to answer this (and thanks a lot!)! In our experiment we collected binary (accept/...
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0answers
17 views

Moderation: Two-way interaction different across groups, but three-way interaction not significant

I'm having trouble interpreting the result of a moderation analysis using the PROCESS macro in SPSS. The following is the structure of the data: Predictor, outcome, and moderator are all continuous. ...
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0answers
36 views

Help interpreting an interaction term from R output of linear regression

So I am familiar with the concept interaction. However in most instances that I have come across, a significant interaction term is in the same direction as the 2 individual terms. However I have come ...
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0answers
8 views

R | Large-Sample Fixed-Effects Interaction using plm

How can I model Interactions with fixed effects for a large sample using plm? I have a panel data set with > 100,000 observations and I am trying to model a dummy-interaction with one of two fixed ...
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0answers
11 views

How to fit a model that forces all points through zero while allowing for interaction effects

I'm trying to build a model to predict the percentage of a target audience reached as a function of the amount spent on several media channels (e.g. TV and radio) and the type of campaign. The fitted ...
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0answers
16 views

manually create categorical variable instead of fitting an interaction term

I am running a logistic regression model and I want to fit an interaction term between a dummy (female) and a categorical variable (risk level; 0/1/2). I was wondering whether creating my variable ...
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1answer
19 views

What is the correct parameter range to choose when conducting a sensitivity analysis?

When conducting a (variance-based) sensitivity analysis, should I set the range of a specific parameter to its maximum allowable range, or restrict it to something more appropriate for my specific ...
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2answers
20 views

Can I rule out moderation with stable regression coefficients?

I have a multiple linear regression, with a and b as independent and c and dependend variables. I want to rule out a moderating effect between a and b. To do that in the easiest way, my idea was to ...
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1answer
15 views

5-way significant interaction with mixed-ANOVA, how to interpret!? (SPSS)

I am analysing results from a study which was a 2 (stimulus type) x 2 (distance) x 2 (speed) x 2 (cardiac cycle) x 2 (grouping variable-between subjects) mixed ANOVA, all of the factors have 2 levels ...
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1answer
19 views

gender specific treatment arms in clinical trial

if we were designing a clinical trial to compare an old and new treatment and there was strong a priori evidence of a treatment gender interaction (ie new treatment does better than old in men, worse ...
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26 views

Two-way MANOVA - No significant multivariate interaction - can I still interpret univariate interaction?

Assume that a two-way mixed (two independent variables (IVs)) MANOVA was conducted. The multivariate interaction effect of the two IVs on the dependent variables (DPs) together was not significant. ...
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21 views

what does it mean when A and B are non-significant but the interaction of the two is significant?

I carried out hierarchical regression model using stepwise method and included interaction terms (predictor variable x moderator variable) in the third step of the model. It was found that only ...
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1answer
31 views

Interpreting a main effect, in the presence of an interaction

In my analysis I have subjects whose blood pressure is measured across time, for two dose conditions (control and drug). I have used a linear mixed effect model and plotted best-fit lines of the BP ...
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0answers
28 views

2 x 2 design. Interaction (moderation effects)

I ma using 2 x 2 design wherein both IDV and moderator variables are categorical along with some continuous variable (control). I want to test the hypothesis for main effects and interaction effects ...
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1answer
8 views

Question about Sample Size Imbalance for Dichotomous Moderator

Sorry if this is a simple question, but I've looked in multiple places and can't find any discussion about it. I have a model where gender is the moderator (1 = female; 0 = male), but the number of ...
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1answer
17 views

How to assess the effects of multiple moderators on a single DV?

For a study I've recently designed, I'd like to assess whether four continuous variables (M1-M4) moderate the impact of five continuous independent variables (X1-X5) on one continuous dependent ...
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1answer
18 views

3-way interaction not signficant; how to interpret subsequent 2-way interactions.

I know there are similar questions on this topic but I have checked all of them and haven't found the specific answer to my (simplistic) questions. There are 3 explanatory variables: A(3 levels, ...
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1answer
23 views

interpreting moderation interaction versus main effects

Moderation interpretation when one predictor is insignificant? My moderation analyses is testing whether self-compassion moderates the relationship between pain severity and emotion (negative and ...
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0answers
16 views

How to compute interactions between vectors of factors

Do you know an algorithm similar to ANOVA to compute interactions between a combination of factors ? For exemple, I have 4 items A, B, C, and D. Each item is described by a set of factors stored in a ...
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1answer
136 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, ...
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1answer
33 views

Test whether effect size in meta-analysis is significant when controlling for moderator

I am using the metafor package to conduct a meta-analysis. I’d like to test whether the overall effect size is significantly different from zero when controlling ...
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0answers
20 views

How do I interpret these categorical main effects in the case of a one level significant interaction in a cox PH model?

So I have a cox proportional hazards model in which an interaction comes out as significant. This interaction is between a categorical variable (tree species) and a continuous variable (diameter at ...
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0answers
122 views

Interpreting interaction between a within-subject factor and a between-subject-factor

I am not sure how to interpret the following interaction between the within-subject factor "prime" and the between-subject-factor "group" (DV are response times). The outcome is slightly not ...
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0answers
18 views

Proper Description of a Hypothesis for Moderation

I read a paper where a person was hypothesizing to see moderation. A was predicting B. They said that for participants at HIGH levels of C, the relationship between A and B would be stronger. ...
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0answers
9 views

R or Stata shortcut to significance test interaction term including restricted cubic splines?

I fit the following model in R using the lme4 package, which is a linear mixed effects regression of outcome "WT_abs_change" (absolute weight change) on various factors, including "ns(WT_dtime, df=3)*...
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0answers
17 views

Performing a two-way ANOVA, I get a non significant Levene's and a significant interaction effect. What it the next step?

In the case described above, our Professor instructs as to interpret the simple effects by using MSwithin of the two-way ANOVA. In case the Levene's test is significant though, he instructs us to ...
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2answers
508 views

Should you use an opinion based variable in modelling? (If it predicts well)

I am using stepwise regression to predict if a customer would give a donation. I used many variables in modelling and a variable called perception_rating is coming out very important. Now this ...
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0answers
25 views

Removing non-significant main effects / interactions

I have a hypothesis that my dependent variable (a clinical outcome) is mediated both by main effects and by interactions between them. I want particularly to demonstrate that (or measure whether) the ...
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0answers
3 views

How Rain fall data series adjusted with % irrigated area in the locality in turn calculate production risk

I want to calculate the production risk based on rain fall data, both the variable is of time series data. we have % irrigated area also. if rain fall less area may be a irrigation by means of canal ...
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0answers
4 views

Absorbing continues-categorical variable interaction term and predicting ex-post

Is there a way of absorbing categorical and continuous variables and then predicting them, because I can not create so many dummy variables in any software somehow I have to obtain the coefficients on ...
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0answers
18 views

Converting Mixed Model lme4 R Syntax to SPSS and Probing Interaction

I am running a mixed model logistic regression in R with the following syntax: ...
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0answers
38 views

Multiple factor interactions with GAM in R?

After reading the documentation about generalised additive models (GAM) in R with mgcv package, I'm still wondering what is the best or most correct way to investigate interactions between two random ...
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1answer
18 views

Covariates and moderator variables

I have a 4 * 3 (both the IVs are categorical) factorial design with two covariates (both are continuous) to run ANCOVA. Can I do a moderation analysis?
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0answers
21 views

Dealing with independent variables that are distinct based on levels of categorical variable.

Marketing campaign effectiveness example. I am trying to model App installs as a function of the following variables Click through rate Ad Spend - CPM (Display) and CPC (Paid Search) Media Type -...
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0answers
37 views

Including many interaction terms in a logistic regression

I have a logistic regression model that is currently of the form: Event ~ Vacc + Age I want to start including interaction terms for different types of vaccine. ...
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0answers
16 views

How to do detect/measure variation causes in steaming data

I have the following situation: I have streaming temperature data on a 1minute time scale for the following: a) Outside temp b) Indoor Building temperature c) Lab temperature (controlled room in ...
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0answers
16 views

contrast for the interaction term

The link (How to setup and interpret ANOVA contrasts with the car package in R?) contains some code as you can see below, which gives an example of how to set up a contrast matrix based on a 2*2 ...
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1answer
34 views

Must a moderator correlate significantly with the dependent variable (Y) in a moderation analysis?

Must the moderator variable correlate significantly with the dependent variable, if I am to do a moderation analysis (multiple regression)? I have a predictor (X) and an outcome (Y). They correlate ...