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

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33 views

Interpretation of the magnitude of the effect of interaction terms

I have a model with interaction terms: $Y = a + b X_1 + c X_2 + d Z + f X_1 Z + g X_2 Z + error$, where $X_1$ and $X_2$ are (0,1) indicator variables and $Z$ is a continuous variable (with a ...
2
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0answers
25 views

Interpretation of Saturated Model vs. Model with Interaction and One Main Effect

Say that I have two regressions: 1) $Y_i = \alpha_0 + \alpha_1 X_i + \alpha_2 X_i*Z_i + \epsilon_i$ 2) $Y_i = \beta_0 + \beta_1 X_i + \beta_2 Z_i + \beta_3 X_i*Z_i + \epsilon_i$ $X_i$ and $Z_i$ are ...
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0answers
30 views

Categorical (5 categories) vs. continuous interaction logistic regression

Apologies if this is comes across as basic - I'm learning logistic regression using SAS while completing md/mph and don't have a lot of stats background. My response variable is dichotomous (1 = EMS ...
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0answers
11 views

Multicollinearity Diagnostics of Mean-Centered Interaction Terms

Interaction terms in moderated regressions exhibit high multicollinearity due to the high correlations with their main effects in case of uncentered data; for Normal distributed variables this is not ...
2
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1answer
56 views

Standardization for regularized, sparse hashed logistic regression

As the question states, I'm fitting large, sparse logistic regressions (with hashed interactions, a la vowpal wabbit) for a machine learning system. The features are on different scales, and I'm a ...
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1answer
31 views

Which tests to run for this interesting study about discrimination?

N = ca. 41000 Dependent variable: subjective wellbeing (values from 1 to 10). Independent variables: job autonomy; income; social trust; political trust; Moderator: ethnicity (dummmy, 1=yes; 0=no) ...
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8 views

Interpreting a significant interaction with only 1 out of 3 dummy variables (arising from same categorical variable)?

I'm running logistic regression analyses (paired observations - we cluster on ID code (=xtlogit in STATA)) with: dependent variable: trust (0/1). independent variable: - eye pictures ...
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8 views

Lower and higher order interactions in mixed factorial ANOVA

What is the impact on interpreting lower and higher level interactions in mixed factorial ANOVAs as the number of variables increases?
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0answers
23 views

Is there moderator or not? Centering and unsignificant b

I am trying to check if the relationship between X and Y is a moderated by M. Here is my model: Y = b0 + b1*X + b2*M + b3*X^2 + b4*X*M + b5*X^2*M where X - independable variable, M - moderator, Y - ...
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1answer
35 views

Interpreting GLM Interaction Contrasts in R (using glht)

I am trying to do a BACI analysis on count data, and I am having trouble interpreting the output from multcomp::glht. I don't understand how the contrast's coefficients are related to effect size ...
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1answer
19 views

Sign of Estimate (Coefficient) of Interaction Terms

I create a linear regression model with interaction term in the model say: $$y=a_0+a_1x_1+a_2x_2+a_3x_1*x_2+e$$ where $x_1$ is continuous and $x_2$ is binary. Now, I have couple of questions: If ...
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15 views

Survival analysis coxph using ridge regression with 2000 variables => “Penalty terms cannot be in an interaction”

I'm doing a survival analysis using coxph function (package survival). I'm using a ridge regression model included 2000 variables but I have a type of error message "...
3
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1answer
41 views

Generating a matrix for regression from long form data

I'm having some difficulty interpreting how to correctly create a matrix input for regression from a long form data source. I have table containing marketing data where each row represents a view of ...
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0answers
43 views

Interpretation of logistic regression output with an interaction effect

I'm currently working on a research problem that requires the addition of an interaction term for each continuous covariate. In other words, I need to determine how the continuous variable changes ...
2
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0answers
58 views

Post hoc comparisions in many groups

I met such problem. I have measured the respiration of animals in in 5 time intervals. Within each interval I have animals asigned to 4 treatments. In my main analysis I consider both: treatment and ...
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1answer
18 views

Difference between a random slope/intercept model and an ANCOVA with an interaction?

I attempted to run an ANCOVA with one binary predictor, one continuous outcome, and one continuous covariate. I found that there was heterogeneity of regression slopes and thus I concluded that an ...
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3answers
67 views

Adding Interaction Terms to Multiple Linear Regression

I am currently running a multiple linear regression, and I am bit confused in regards to how to properly add interaction terms to the model by hand. All of the variables I am using are continuous and ...
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0answers
29 views

deal with interaction that is composed of correlated variables in multinomial logistic regression

I'm trying to build a model between three variables: y=user interest, x1=time, and x2=space. All the three variables are categorical, with the response variable y=user interest being described by ...
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0answers
13 views

Modelling interactions with only a subset of the levels of a factor in R [migrated]

Let's first look at lm. I have a continuous explanatory $X$ and a factor $F$ modelling seasonal aspects (in the example 8 levels). Let $\beta$ denote the slope ...
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0answers
21 views

Selecting proper Linear Model with interaction considered

Data consists of Temp(3lv Factor), Water(num), Fert(num), and Growth(num). Considered model is LM with DV: Growth, IV: Temp with Water and Fert as covariate. Fitted 2-Factor ANCOVA (Full Model) and ...
2
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1answer
34 views

Interaction between time-variant and time-invariant variable in FE model

I want to estimate the effect of several variables $x_{1,it}$, $x_{2,it}$, $\dots$ on $y_{it}$. All of these variables vary across countries $i$ and time $t$. I use OLS to estimate a model with ...
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0answers
25 views

Multiple interactions are hard… Difficult difference-in-difference design UPDATE

I am trying to estimate a difference-in-differences model with some complicated interactions. I have panel data on the supply of some production input to firms from two groups. The supply of this ...
2
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2answers
44 views

Surprise: Why is my factor not significant?

I am analysing the performance of a large population in exams using a binary (pass / fail) outcome. In the majority of exams, women out-perform men. However, when gender is included with other factors ...
3
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1answer
67 views

How should I implement this interaction between a continuous and categorical predictor?

I have a continuous outcome variable. I understand that if I have a binary predictor, and a continuous predictor, and an interaction, then the model looks like this: $y_{i} = \beta_{0} + ...
3
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0answers
34 views

How to check variables changeable dependency in R?

I would be very thankful if somebody could help me and explain the answer in simple terms. I have y, x, z variables. They are countinuous, no missing values. y is dependent variable, x and z ...
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13 views

main effects only significant when modelled with an interaction [duplicate]

model = lm(m ~ xy + a + a2 +y) With an interaction (xy) Coefficients: Estimate Std. Error t value Pr(>|t|) (Intercept) -1.8840405 0.9174444 -2.054 0.0404 * x 1.3610892 ...
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13 views

Significance of multi factor interactions in linear regression

I was told by a professor of a stats course last year (who I can't now contact), that it is unlikely to find statistically significant interaction terms using more than three factors. Is this true? ...
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1answer
23 views

interaction and significance

How do you interpret interaction terms between two categorical variables if Y is significant, Z is not significant, but Y*Z is significant. Do you include the interaction term in the model, or do you ...
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0answers
13 views

Multinomial logistic regression and interaction [duplicate]

I am running a multinomial logistic regression and have my final model, but now want to check for interactions between my two exposure variables and my independent variables. When I run this, one of ...
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0answers
37 views

What´s the difference between the p-value and interaction p-value?

I need to interpret the logistic regression data shown in the figure. Q1-4 represent continuous values of height measurements divided into quartiles. The covariate is mean weight. Can you tell me what ...
1
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1answer
55 views

Measuring efficiency with an interaction in a Tobit model?

I am interested in how to interpret outputs generated with marginal effects after estimating a Tobit model. I am using Stata 13, so I figured I'd use the command margins - which I find very helpful. ...
2
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1answer
67 views

Is it reasonable to drop an interaction term?

I'm regressing a model Y = X1 + X2 + X1X2 and the result turns out that none of them are significant. However, if I drop the interaction term, X1 becomes significant. Is it ok to drop the interaction ...
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0answers
9 views

Local Sensitivity Analysis

I am tring to have a comprehensive idea about sensitivity analysis. I found numerous papers, books, and serves about global senstivity analysis methods. Coming to the local sensitivtiy Methods, I try ...
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0answers
6 views

Using interaction terms to exclude sample members who do not meet certain conditions?

I believe this might be a specific application of the non-compliance problem in experimental design and estimating treatment effects, but I could be wrong. I want to model the impact of certain ...
0
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0answers
27 views

Chi-square test for interaction

I want to look at the interaction between two independent variables on a binary dependent variable. I can't use a binary logistic regression because I have a small sample size. Can I do this using a ...
0
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0answers
9 views

interaction effect on consecutive gestures from different sets

I am conducting an within-subject experiment in which each participant has to perform 2 consecutive gestures with one arm. (with repetitions). To make it simple, let's say that I have 2 sets of ...
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0answers
21 views

Interpretation of linear and quadratic interactions

I'm working on building and interpreting multilevel models. In one, I'm predicting binge episodes over time and using a linear time by baseline characteristic interaction as well as a quadratic time ...
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0answers
27 views

Non-significant interaction effect

I currently have a regression where adding an interaction effect between two significant variables (a float and a boolean) makes them non-significant. Given that this interaction effect is not ...
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2answers
72 views

How to interpret this interaction in R?

How would you interpret this interaction? The structure of the data is all integer variables. Inc.fix= income, age.fix=age, profit99= profit ...
1
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1answer
50 views

How to interpret my coeff/ORs when the main effect of my two predictors is significant but not the interaction between the two?

Apologies as this has been posted before in similar topics but still I am trying to stretch my brain to understand it. I have panel data, I am looking at both binary and count variables as outcomes ...
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0answers
17 views

Explaining mixed-model interactions with ANOVA?

I have searched through the answers on this forum and I couldn't find any detailed explanation to my question about linear mixed models. Here is my setup: 4 groups with treatment X (one of which is ...
2
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1answer
68 views

Does a factor-by-factor interaction term have any literal interpretation?

Following the explanations in What is the baseline level in a factor-by-factor interaction?, it is my understanding that a factor-by-factor interaction term has no literal interpretation. At the very ...
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0answers
31 views

Interactions and Multicollinearity

I have a question concerning multicollinearity in OLS. I built a very simple model: y = a + x(x) + y(x) + e. In this case x is a significant predictor, y is not. Both of them are time related ...
3
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1answer
56 views

Reduce subsetting of the dataset?

I collected a lot of trapping data of a certain rodent species. I constructed a model to see what affects the individual's activity. I constructed this LM (linear model): ...
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1answer
53 views

Main effects significant but no significant interaction

My hypothesis for my dissertation was to find an interaction between two predictors; however, my results showed that the interaction was not significant but the main effects were significant.  In my ...
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0answers
21 views

How can we observe interaction?

Are there graphical methods to determine whether there are some sort of interaction between two variables towards the response variable? Thanks!
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41 views

How does one graph a 3 way interaction on excel? Also. how do you explain a 3 way interaction?

So my 3- way is between Prime x ethnicity x gender, not sure how to graph it and how to verbalize it. Any ideas are greatly appreciated. Thank you.
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1answer
45 views

Creating an interaction term with 2 continuous variables: What to do?

I want to create an interaction term in SPSS on two continuous variables (ticket price and household income) in order to use this interaction term in a multiple regression model and test whether my ...
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1answer
17 views

Duplicate AICc values for multiple models with interactions

I am going through a model selection process with a mixed-model with 3 variables: A, B, and C. B and C are orthogonal factors. B or C may interact with A, so my full model would be: fixed: ...
2
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1answer
47 views

What is the baseline level in a factor-by-factor interaction?

What is the baseline level for a factor-by-factor interaction term in multiple regression? Consider this example from Fox 2003. In the regression below, these two variables are categorical: ...