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

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11 views

Assessing Interactions with MANCOVA

The data I am working with has 1 IV (categorical with 2 groups), 5 DVs (all continuous), and 2 covariates (also continuous). I ran a MANCOVA in SPSS but I am running into a problem. I would like to ...
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37 views

How do I fit a linear regression model in R with interaction but with zero intercept?

I have an experiment where we measure the energy used by a building and want to regress this energy linearly against so-called degree-days, calculated with two different methods. The data looks like ...
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3answers
65 views

How to best model interaction effect of two continuous predictor variables?

Consider the following problem: In a logistic regression model, we believe that two continuous predictor variables $X_1$ and $X_2$ impact the probability of event. It is hypothesized that the ...
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27 views

Issue with linear mixed effects model and interaction : any alternate method?

I have a variable (Y) which I'd like to know if it can be explained by linear regression with two other variables (A and B) or the interaction of A and B. Let's say, to simplify, than I have two ...
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7 views

Multiple regression with 5 continuous IVs and one continuous moderator in SPSS

I am trying to test a multiple regression model with 5 continuous independent variables and 1 continuous dependent variable. Also, I'm trying to test the moderating effect of 1 continuous variable on ...
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7 views

Interpretation of an interaction term in survival analysis

I'm struggling with an interpretation for an interaction analysis. In the univariable Cox analysis, the HR for variable 1 is 1.03 (95%CI 1.02-1.04) and for variable 2 is 0.37 (95%CI 0.26-0.55). In ...
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28 views

Is feature complementarity different from feature interaction?

I am writing a conference paper in which I have a sentence like "...complementary/interactive features...". This sentence ...
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1answer
15 views

Hypothesis Testing Multiple regression with dummys and interaction

I have a model $$Y_i = \beta_{0} + \beta_{1} *P_i + \beta_{2}*B_i + \beta_{3}*E_i + \beta_{4}*B_i*E_i+u_i$$ where Y is a Rating, P is the price, E is the educationional level ( 0 no higher education; ...
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34 views

adding interaction term gives opposite relation

I am trying a mixed model in R (lme4). The objective is to evaluate the average glucose level of patients in a hospital is decreasing in the last four years. The model is simple that glucose values ...
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30 views
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13 views

Building interaction terms with dummy coded categorical predictors with more than 2 categories

I would like to perform a linear regression on a data set with a continuous DV (score). I do not understand how to interpret interactions made with the dummy coded variables that have a reference ...
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5 views

1 continous predictor and dependent variable measured in 4 different conditions - multilevel analysis?

My experimental design involves one continuous independent variable (score in the questionnaire) and continous variable which is measured in 4 different conditions (different type of the stimuli). I ...
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10 views

Do I need to create new interaction terms in a linear model that uses a logit transform of the orignial response variable?

I've created a linear regression model in R that contains the following interaction terms. ...
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31 views

Sample size needed to detect a three-way interaction?

I am hoping to propose a study for which the predicted outcome would be a three-way interaction. I am wondering if this is going to be possible at all with the resources at my disposal, or if the ...
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13 views

How to interpret Interactions in a spatial fixed effect model

My units of analysis are racial groups nested in Metropolitan Areas, such that I have an observation for each racial group that is present in a Metropolitan Area. I include a fixed effect for the ...
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0answers
6 views

how to use a comparison between two ordinals as a regression predictor

I'd like to predict which species is likely to dominate the other in a pairwise interaction between species. In the literature on dominance hierarchies ("pecking order"), what's usually considered to ...
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0answers
27 views

Interactions with a time invariant control in a fixed effect model

I am looking to add individual-fixed effects to a panel model. I have an interaction which includes a time-invariant variable (e.g. gender) interacted with a time varying variable (e.g. ...
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3answers
75 views

Why include insignificant main term when interaction term is included? [duplicate]

Most of the statistics material suggest that when the interaction term is significant, even though the main effect term is not significant, we still keep the main effect term. For example: $$z = a + ...
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19 views

Does testing multiple interaction terms result in multiple testing problems?

I have been testing interaction terms in a regression model using likelihood ratio tests, and dropping any terms from the model if insignificant. I do not want to assume a priori that there are no ...
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14 views

Treament By Covariate Interactions with Propensity Score Weighting

I am trying to estimate the causal effect of a treatment on an outcome using propensity score weighting. I estimated the propensity scores and verified covariate balance with a number of covariates, ...
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17 views

Centering in the presence of interactions with categorical predictors?

I understand that always scaling covariates prior to regression analysis is controversial advice. See for example Andrew Gelman's blogpost and comments, or many crossvalidated questions such as this ...
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1answer
39 views

How to plot a 3-way interaction with 2 categorical and a quantitative variables

There is a significant 3-way interaction in a data-set I'm working with. The interaction involves 2 categorical (with two levels each) and a quantitative variable. I think I understand how to ...
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1answer
58 views

Interaction term in a linear mixed effect model in R

I am attempting to analyze the effect of two categorical variables (landuse and species) on a continuous variable (...
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1answer
26 views

Justification for adding interaction terms to a multiple regression

If you have no domain knowledge, is there any justification for adding interaction terms to a multiple regression? If so, is there any intelligent way to select them? With a large number of ...
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27 views

Finding causality and/or correlation within a dataset [closed]

I have 3 data sets (3 days) which I need to analyze. My goal is to show what the interaction between aerosols and plants is, if and how they impact on plant photosynthesis. These are my variables: ...
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1answer
35 views

Correlational meta-analysis and moderators

I have 3 correlations between A and B through 3 different studies : ...
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0answers
7 views

How dummy variable interactions affect least squares estimates

I have a dataset on earnings data and running various regressions have found that ethnicity is not a strong indicator for women but it is for men whilst BMI is significant for women but not for men. ...
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32 views

Number of interactions terms in a panel regression set-up : Triple interaction terms

In my sample, I have two types of funds. I would like to see if Type A fund shows different results than Type B. The way I distinguish them is through a dummy variable (with Type A fund having the ...
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10 views

Why did the coefficient of an independent variable changed after putting controls and interaction effects into the regression? [duplicate]

Does the correlation sign of the independent variables play a role for the change? Why one of my coefficients increased while the other one decreased? Can I explain the downward and upward bias that ...
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14 views

Interpretation of ANCOVA interaction term

I have some doubts in how to interpret the interaction term in an ANCOVA using R since in other statistical programs this term is not provided. If I am right, one assumption of ANCOVA is the ...
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11 views

Why in a multi-factorial ANOVA with a random variable, we use MSinteraction error term for independent variables instea of MSerror?

So can some one please explain this to me in simple language? I know that random variables introduce more uncertainty in our data, but that is perhaps not enough for an answer. Why do we specifically ...
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24 views

multiple regression in R controlling for categorical variable

I am trying to run a multiple regression with 6 continuous variables (within-subjects) with the interaction variable of age group (between subject, 2 levels). I want to know to what extent the ...
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20 views

Should I change interaction_average and/or covariate_average with mcp function from multcomp [closed]

I am using Dunnett's test to compare treatments to a control in an ANCOVA model that I build. Sometimes, however, the final ANCOVA model contains an iteraction term. I can still perform Dunnett's test ...
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3answers
97 views

How to read the Interaction effect in multiple linear regression with continuous regressors?

If the interaction happens between a continuous and a discrete variable it is (if I'm not mistaken) relatively straightforward. ...
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1answer
34 views

Interpreting interaction terms in Cox Proportional Hazard model

I am new to survival analysis, so forgive me if this questions is stupid - but I couldn't find the answer anywhere else. We are looking at readmission to a treatment program, which is defined as ...
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1answer
30 views

ANOVA with and without interactions giving different values for main effects

I have measured Copper content in fishing nets. I have 2 independent variables - treatment of the net with 4 levels and ...
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16 views

Interaction term between a dummy and a trend — does it make sense?

I am attempting to estimate the simple effect of membership in a regional arrangement (say, a regional free trade area) on a dependent variable using panel data. Membership is modeled as a binary ...
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3answers
190 views

Which statistical model to use when trying to find the beginning of a time-dependent increase

I have a repeated measures data set with time as the independent variable and a single dependent variable, y. That is, for each subject, I have a certain (small, from 1 to 3) number of measurements. ...
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1answer
12 views

Can interactions save power in a regression (vs. stratification)?

I have data with about 700 observations total. There are 9 subgroups in my sample with sizes ranging from 54-96. I want to use linear regression to explore how 8 independent variables might predict ...
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1answer
20 views

Testing additivity vs. interactions [closed]

I'm interested in differentiating the additivity of two factors versus if their interaction produces an effect. For example: Factor A produces effect of level 20. Factor B produces effect of ...
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1answer
34 views

Removing interaction term from repeated measures two-way ANOVA in R: Anova() function in car package

My question pertains to excluding the interaction term (once it's deemed insignificant) in a two-way repeated measures ANOVA using the Anova() function in the ...
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12 views

(How to Mean Centering for interaction effect?) Social Research case

I want to ask on how to mean centering in case data in SPSS are all on likert scale. I have googled some information that steps in mean centering are: calculate mean of variable Substract variable ...
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1answer
19 views

how can we know there is interactions between explanatory variables or quadratic when we write the generalized regression model?

How can we know there are interactions between explanatory variables or quadratic when we write the generalized regression model? For example: ...
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1answer
69 views

Effect of a categorical varaible on relationship between x and y: model as an interaction with x, or model y/x with category as main effect?

I have some data where the relationship between x and y is modified based on which category an observation belongs to. Here are some sample data, as well as a plot of x vs. y, generated in R: ...
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32 views

Difference in difference with interaction

I am trying to estimate a causal effect using a difference in difference estimator. I suspect there will be a different effect for small and large firms. I am interested in this different effect. I ...
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1answer
36 views

Centering variables in regression leads to the same model of original variables, why still doing that?

The regression model y= b0+ b1 x + b2 x^2 + b3 x^3 and the second regression model y = b0 +b1 (x-u) + b2 (x-u)^2 + b3 (x-u)^3 where u is the mean of x These two models lead to the same curves, or ...
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1answer
55 views

Meta-analysis and meta-regression results don't agree

In the context of a (multilevel) meta-analysis, I want to caluclate grand effect size estimates for subsets of data corresponding to the levels of a categorical variable. Using the example below, I'd ...
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53 views

Model multiple imputation with interaction terms

According to the documentation of the mice package, if we want to impute data when we're interested in interaction terms we need to use passive imputation. Which is ...
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0answers
18 views

How to construct contrasts for a linear model with interactions?

I have trouble figuring out how to set up contrasts for a linear model with interaction terms. In the following example, how do I construct contrasts so that I test for the differences of species A - ...
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40 views

interpretation of coefficients in multiple regression with categorical and continuous predictors

I have been struggling with the interpretation of the coefficients in my multiple regression model and I hope you can help me with that! Thanks in advance for reading the long explanation that follows ...