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

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3
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27 views

test interactions for multiple regression with many predictor variables

I have a data set with around 25 predictor variables. If I am planning to build multi-regression model against this data set. What are the general approaches to test the interactions of these ...
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1answer
46 views

Interpreting a linear mixed effect model's interaction term

I am a biologist and am attempting to analyze the effects of time and location on depth. I was told I needed to use a mixed effects model to account for the random variables of Individual and tracking ...
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0answers
7 views

Without interaction, an IV has a significant negative coefficient, but the coefficient became significant positive after interaction. Why?

Before interaction: IV1 sig neg IV2 sig pos After interaction: IV1 Sig pos IV2 Sig Pos IV1*IV2 Sig Neg Is that reasonable? How to explain the change of the sign from significantly negative to ...
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1answer
56 views

Specifying Cross-Level Interactions in LMER

I am trying to figure out if it's okay to specify cross-level interactions in a hierarchical model with fixed effect predictor variables at both levels using the ...
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0answers
39 views

Variance in significance with interaction term

I try to estimate the effects of NatRent (Natural resource rents in % of GDP) on GDP growth per capita (in %). When I include a Rule of Law (a measure for institutional quality) the coefficient of ...
1
vote
1answer
32 views

LSmeans - Unbalanced data with interactions

I wish to analyze an unbalanced data set with 3 variables Tleaf, Tair, and orientation (factor with two levels). Considering the effect of the factor "orientation", I wish to determine if "Tair" has a ...
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0answers
37 views

Interactions in Propensity Score Models

I am doing an analysis to see if a first-year seminar has an effect on student retention in college. Students choose whether or not to enroll in the seminar on their own, so it seems like it makes ...
2
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1answer
21 views

Which mean to use for centering variables when sample definition varies

I am centering variables that enter interaction terms in my linear regression. To check the robustness of my results, I exclude certain cases from the original sample, and re-run the regression ...
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0answers
15 views

Moderated regression with categorical predictors

I would like to do a moderated regression with SPSS. My problem is that the independent variable (predictor) is categorical, wheras the moderator as well as the dependent variable are interval ...
0
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0answers
18 views

Interpreting an interaction in the presence of main effects

I'm having a crisis of confidence in my stats and I was wondering if somebody could help me. I ran a 2 x 2 x 2 x 3 repeated measures ANOVA and got: 2 main effects 3 2 x 2 interactions and a 3 way ...
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0answers
9 views

mixed within-between ANOVA. I have a significant interaction but no significant main effect

I am currently trying to interpret the output of my mixed within-between ANOVA. I have 2 groups (experimental and control) and 2 time points (pre and post intervention).The dependent variable is a ...
1
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1answer
32 views

Using interaction terms in an MCMCglmm

I am using MCMCglmm models in R, with hierarchically nested data. The basic structure of the data is as follows - each dyad is a unique combination of focal/other: ...
2
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1answer
23 views

Explaining Non-Significant Moderations

Schools often teach us how to conduct and interpret Moderations. What they don't teach us is how to explain why a moderation didn't work out for statistical/methodological reasons. Assuming that the ...
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0answers
25 views

Sample size for a moderated hierarchical multiple regression analysis?

I am having a challenging time finding out the necessary sample size for a moderated hierarchical multiple regression analysis. The first five steps of the regression will include the 17 variables ...
0
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0answers
29 views

How to interpret 3 main effects when an interaction exists for only two of the variables?

I've been searching for interpretation guidance regarding the below problem, but all the resources I've seen have been fully crossed (i.e., all variables included in the interaction term). Below is a ...
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1answer
22 views

Metafor package: RMA and testing for interaction in two studies (Altman & Bland 2003)

I have traditionally used this simple test of interaction (http://www.bmj.com/content/326/7382/219) for comparing effect sizes between studies, and I would like to start performing it in R. Although I ...
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0answers
10 views

in a partial mediation relationship, can the independent variable and the mediator moderate each other?

Let's say age predicts experience, and experience predicts perceived reputation of doctor. Age also predicts perceived reputation directly, and moderates negatively the relationship between experience ...
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0answers
8 views

Is this a confounding interaction: using demographic data in a fractional factorial design?

I've created and run a choice experiment (conjoint analysis) using a fractional factorial design 3 x 3 x 3 x 3 (four factors with three levels each). I also collected some demographic data (age, ...
0
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1answer
58 views

Interaction terms and effect sizes in multiple regression

I know there are similar questions on here, but I can't quite find an answer that covers all of what I need. I am running multiple regression in r with two predictor variables and sometimes an ...
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0answers
17 views

how to interpret Interaction term in generalized linear model [duplicate]

I have an experimental condition (dummy-coded) as an categorical predictor, and one continuous predictor variable (treatment frequency). The dependent variable (Y) is consumer satisfaction This is ...
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0answers
20 views

Interactions between Dummy codded categorical variables in R

I have estimated a mixed-logit model in R.Here are my Results ...
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1answer
39 views

How should I interpret a factor that is significant both (1) in linear form in interaction with another factor and (2) in its quadratic form?

Our study aims to identify and understand how several ecological factors relate to parasite abundance in a colonial animal. However, we are uncertain on how to interpret a factor (density) that is ...
2
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1answer
56 views

Design of Experiments

Suppose a dermatologist wants to study the effectiveness of two different preparations of a skin lotion using two different forms of application, such as one versus two applications per day. She has ...
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2answers
72 views

Graph with 2 interacted continuous predictor vatiable

When using glm(link=logit), I detected a significant interaction between two continuous predictor variables. How can I present the results visually using R?
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2answers
105 views

Interpretation of multiple logistic regression with interactions in R

I am trying to look at whether 2 variables (one dichotomous categorical and one continuous) predict the occurrence of a dichotomous categorical dependent variable. ...
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3answers
37 views

Results with and without interaction

I'm working on an analysis with another person. First we did a logistic regression with study group and variable X. They were both significant. Then we added the interaction between study group and X ...
0
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1answer
31 views

Fractional Factorial Design

In a $2^5$ design, it is believed that only the main effects $(A,B,C,D, E)$ and $AB,AC$ interaction effects are non-zero. I need to construct a fractional factorial with minimum number of runs which ...
0
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1answer
26 views

$2^{5-2}$ Design : Alias Structure

$2^{5-2}$ Design Design Generators: $D=AB\quad E=AC$ Defining Relation: $I=ABD=ACE=BCDE$ $$\text{Aliases}$$ $$A=BD=CE=ABDE$$ $$B=AD=ABCE=CDE$$ $$C=ABCD=AE=BDE$$ $$D=AB=ACDE=BCE$$ ...
3
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1answer
131 views

How to interpret non-significant interaction term in linear regression?

I have difficulties interpreting an interaction term in a linear regression with regards to my hypothesis. Consider this basic example: H0: Better school grades lead to higher income and this ...
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0answers
32 views

The a priori power of test for a simple effect within a 2x2 ANOVA

I need to know about the power of a simple effect that follows from a 2x2 ANOVA interaction. Let's call the factors in this design GROUP(Patient, Control) and MANIPULATION(Expectation, Random), ...
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0answers
23 views

Significance of linear combination of two insignificant regression parameters

I'm running a model with an interaction term, of the general form: $Y=b_1X_1+b_2X_2+b_3X_1X_2$, whereby $X_2$ is a dummy variable and $X_1$ is continuous. Neither $X_1$ nor $X_2$ turn out as ...
0
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0answers
29 views

Not normally distributed dependent variable in moderator analysis

I have been running a multiple moderator analysis in a pretty simple model. X are Google search queries normalized to 0-100. Y are the new registrations of cars in one country and one moderator. ...
0
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0answers
11 views

Measured moderator, which is influenced by an independent variable

I have a measured variable, which is found to be influenced by an independent variable (i.e., experimental conditions). I will report this in the first part of the result section. Also, as an ...
0
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0answers
26 views

Interaction in regression [duplicate]

In my regression model of BMR on age (yrs) , gender (1=male, 0=female), height and weight. The regression equation obtained is: BMR = 1232.059+13.281 weight+3.954 age+192.214 male-3.471 age:gender. ...
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1answer
36 views

AICc and K for categorical factors and interactions

I am new to multimodel inference. I am trying to create a model that has multiple categorical factors and possible interactions. For example say that my model is... Y ~ X1 + factor(X2) + ...
0
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1answer
79 views

what is the difference between collinearity and interaction?

I cannot differentiate clearly between "interaction" and "collinearity" in multiple linear regression. For me these terms are related but not the same. I have searched the forum but could not find ...
2
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1answer
44 views

Omitting a moderator

I'm wondering what the effect is if I don't include moderators in my model? Is this the same or different from an omitted variable bias? I am having a hard time grasping this conceptually. More ...
2
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1answer
33 views

Is it acceptable to not include high-order interactions (3-way and above) in the model when they are not by themselves of interest?

Is it acceptable to not include high-order interactions (3-way and above) in the model when they are not of interest and not part of the hypothesis that is being tested? NB. I am not talking about ...
0
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3answers
55 views

Covariate no longer significant after inclusion of interaction term

I'm trying to interpret some results here, and just want to make sure that my logic is sound. I'm predicting a binary outcome with a categorical predictor (gene level coded as 0, 1, or 2 dependant on ...
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3answers
97 views

I do not have hypotheses for my research and I have got only categorical data. what kind of data analysis can i conduct? also

I do not have hypotheses for my research and I have got only categorical data. what kind of data analysis can i conduct for correlation between variables? also is chi-square used only for hypotheses ...
0
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1answer
35 views

Find the amount of variation due to another covariate

I'm trying to explain a binary outcome (cardiovascular disease) with a categorical predictor (gene level, coded as 0, 1, or 2 depending on the number of risk alleles present). I'm trying to determine ...
0
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0answers
14 views

Should I run Hierarchical regression to test moderation? Why?

I am an undergraduate student who currently preparing for my thesis paper. In my design, there is total 4 variable (1 predictor, 1 moderator and 1 outcome variable, all of them is in continuous ...
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0answers
57 views

Statistical Analysis help for thesis - Correlation, Probit, Tobit and Moderation

Hello CrossValidated users! I am writing here cause I need some guidance on my statistical analysis which has turned out far too complex for my basically begineer stats skills and my self research. ...
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0answers
26 views

Interpreting results from a mixed model with interactions

I need your help interpreting my model's results. To make story short, I have a continuous dependent variable $Y$, and two factors $A$ and $B$, each with $2$ levels $(A_1, A_2, B_1, B_2)$. My main ...
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3answers
63 views

Ratio of explanatory variables in multiple regression

I wonder if anyone has any links or advice on specifying a ratio of two explanatory variables in a linear regression? That is, specifying the two independent variables plus their ratio. We have data ...
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0answers
22 views

Factorial design for interactions with ordinal DV

I want to make a 4 question, multiple choice survey in which each question asks about an analogous range of actions for slightly different scenarios. Each participant would only be administered the ...
0
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0answers
27 views

main effect and interaction effect

I faced difficulty with my data analysis output. I had two factors with split plot design. Separately, the main effect of the two factors on soil pH was significant. But their interaction effect was ...
2
votes
1answer
46 views

Metafor package: Interpreting rma model with two (or more) moderators.

New user of both stackexchange and R here. My questions are about mainly about interpretation, and my dataset is quite large, so I have not included my dataframe. I have two queries (in bold). Using ...
0
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1answer
51 views

How to run main effects and interactions in a stepwise regression?

I am using multiple regression with the backward elimination method. I have one control variable (social desirable responding) and four predictor variables (gender and three self-esteem constructs). ...
0
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2answers
22 views

Interaction between variables

I would like to regress basal metabolic rate (BMR) on height, weight, age and gender. How do I do this taking into consideration the interaction between the variable? Wouldn't I have to consider ...