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

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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
46 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 ...
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1answer
30 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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10 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 ...
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0answers
11 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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17 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 ...
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1answer
40 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
36 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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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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21 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
37 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: ...
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96 views

^ symbol in lm() in R [migrated]

I asked this question in Stack Overflow: http://stackoverflow.com/questions/29710525/symbol-in-r-lm I feel like here would be a better place to get an answer. What exactly does the ^ symbol do to the ...
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1answer
39 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: ...
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21 views

How to interpret factor by factor interactions?

I'm a bit confused on how one should interpret factor by factor interactions, and what interpretations can be validly extracted. Consider this example from Fox 2003. In the regression below, these ...
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0answers
43 views

How does the presence of factors affect the interpretation of the other coefficients in a regression?

The answer to Interpreting coefficients of an interaction between categorical and continuous variable contains a phrase that seems to have some significant impact on how coefficients are interpreted ...
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1answer
19 views

Standardize within cohort or standardize within entire sample?

Suppose I'm interested in regressing variable A on variable B. I have two cohorts and want to be sure that there is not an interaction between cohort and variable B, so I include that in the ...
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1answer
69 views

Logistic regression: my main effects lose significance when I add my interaction effects. Why?

I have a dichotomous dependent variable for a 2x3 experiment. There are about 30 observations in each cell, for a total sample size of about 180. Each person was only in one cell. The dependent ...
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1answer
43 views

GLM Interaction Lasso

Apparently the stepwise produce in R is not a good way to automatically select the best glm model. Different sources suggest using lasso instead. I had a look at the glmnet packages but I do not ...
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1answer
56 views

Effect of categorical interaction terms with random forest machine learning algorithm

Thanks in advance for the help. I have moderately large dataset (around 7000 samples) with numerous categorical predictors and a single binary response. All of the predictors are categorical. ...
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23 views

Interpreting interaction terms

I have 9 regional dummies (using only 8 in a regression equation to avoid collinearity, omitted the richest region) and a few explanatory variables such as formal housing (1 if an individual lives in ...
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0answers
35 views

Confused about whether to use t-tests or ANCOVA or ANOVA

I am investing whether vitamin C supplementation can attenuate creatine kinase increases after a strenuous workout. My participants are divided into two groups, VitC group and a Control (no ...
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2answers
84 views

Interpretation of continuous variable in dummy-continuous interaction

Similar questions have been asked before, but all of them focus on the dummy or interaction term. Say run an OLS regression on the model: $\ln( housePrice )= \beta_1 \times pollutionLevel + \beta_2 ...
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1answer
34 views

Interaction term

I wanted to ask about interaction term. I am having an ordinal probit model. The two of the independent variables that i have are discrete 1-Uni( a 0,1 dummy variable) and second is continuity (1,2,3) ...
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1answer
20 views

Using both treatment and sum coding in a single model?

I am running a regression with two independent variables. The dependent variable is accuracy. I am looking to see if being at Level 1 of Factor A makes you more likely to be correct than being at ...
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1answer
18 views

Some Terminology in Multilevel Analysis

What is the meaning of the following terms in multilevel analysis: cross-level interaction; micro level; macro level?
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69 views

Can you leave out more than one dummy variable to have more than one variables in the reference category?

For example, in the simple OLS regression: $y = a + b_1x_1 + ... + b_kx_k + \varepsilon$ if your dummy variable $d$ has 10 categories, could you include just one dummy variable for instance: $y ...
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why is there a difference between these two interaction plots

I was trying to see if there is any interaction between temperature variable and family variable on the photosynthetic rate (Assimilation) and for this purpose, i have generated interaction plots. ...
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1answer
67 views

Can you interact the entity in fixed effects estimation?

I have estimated housing affordability (RRI) by fixed effects using the equation below: The 'r' represents regional effects and 't' represents time effects. This estimation works in Stata but are ...
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16 views

A question about multifactor anova

I am trying to look to see if there is any effect of temperature, family, cross type and genotype on photosynthesis rate. So here, photosynthesis rate is a response variable and the rest of them are ...
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0answers
16 views

Use Fisher's exact test to identify interactions?

Assuming that I have data with say 3 predictor variables and 1 response variable as such: ...
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0answers
23 views

“interact.gbm” in package gbm vs. “gbm.interactions” in package dismo

The reference manual for the gbm package states the interact.gbm function computes Friedman's H-statistic to assess the strength ...
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1answer
44 views

Need help in understanding continuous-dummy interaction in OLS regression

I am having some conceptual difficulties in understanding and interpreting interaction terms (between a dummy and a continuous variable) in OLS regressions. I was hoping someone could help me out. I ...
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1answer
29 views

confidence intervals around lines from glmer in lme4

I have spent a large amount of time trying to figure out how to generate a desired plot, and was wondering if any one can help. The plot is to illustrate an interaction between 'time' and 'group' on a ...
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20 views

Multilevel models benefits vs. separate group models

What are the benefits of multilevel models vs. running a separate model for each group? My understanding is that MLM offer a method to effectively model interactions against all the base predictors. ...
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13 views

Interacting lagged variable with dummy: factor variable and time series not allowed [migrated]

I am trying to run an Arellano-Bond regression to explore whether the impact on my dependent variable varies according to exchange rate regime, i.e. does economic growth differ when remittances go up ...
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42 views

In stratified analysis should beta estimates from main effects remain constant when an interaction is added? [closed]

I run stratified analyses by a factor variable and found estimates for both groups to be significant. Then I have included an interaction term. The results from this analysis revealed that the ...
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1answer
15 views

Nesting v. interaction in LMM

I have a continuous response variable, a continuous predictor (P1) and a variable (elevation, P2) that could be treated either as continuous or categorical (I guess?). I also have an ID as the random ...
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30 views

How does one interpret a demeaned log interaction term?

I am having problems interpreting my regression equation. I want to know the effect of an increase in variable $x$ on $y$ for different values of $z$, but as it's in logs and the interaction term is ...
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21 views

Linear Logistic Regression where Dummy variable is strictly dependent of other covariates

I want to do a logistic regression for something being granted or not. In this I have independent variable that is dependent of a dummy variable. For example, I want to regress ...
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2answers
49 views

Large differences between raw (plotted) data and least-squares means from mixed model

I’m analysing data with mixed-models (using the afex package which I believe is based on lme4) from an experiment that had a ...
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0answers
15 views

Two-way interaction of shared variable in econmetric

I am trying to build a fixed effect model and this is my model at the moment X + Y + Z + XY + XZ My hypotheses are interested in XY + XZ but i have consulted a few people who told me in order to ...
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1answer
30 views

How to show the combined effect of two covariates in a simple regression?

Say I want to build a simple model, and I have four variables available to me: Age, gender ($D_1$, 1 is female, 0 male), income, and whether the person is Hispanic or not ($D_2$, 1 is Hispanic, 0 ...
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1answer
31 views

Dummy variables for people and time

I have panel data for people over a number of years. People can be categorised based on a certain characteristic, X. Individual's yearly observations can be categorised based on whether a particular ...
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1answer
21 views

Interpretation of Interaction Term with Dummy [duplicate]

I am trying to interpret the following model: y=a1+a2*x+a3*d+a4(x*d)+e where y= growth rate x=debt d= dummy high debt ...
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15 views

Interaction model with measurement error without replicate measurements

I am currently working on a simple OLS model with two independent variables and one dependent variable: \begin{equation} \ Y_i = \beta_0 + \beta_1 X_i + \beta_2 S_i + \beta_3 X_iZ_i \end{equation} ...
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1answer
72 views

Boosted trees and Variable Interactions

How can one see in a Boosted trees classification model, which variables interact with each other and how much? I would like to make use o this in R gbm package if possible
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27 views

Multicollinearity error in interaction model

I have a question about multicollinearity in the ordinal logistic regression. I have a cohort binary variable (i.e. 1 = canada, 0 = U.S. ). I then have a variable with 3 levels called it Smoking(1 = ...
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39 views

Interaction in Multiple Regression with Lagged Variable

The problem I'm trying to solve is as follows: X is a strong predictor of Y, both measured at time T, controlling for other IVs. Based on theory, some people say this supports the hypothesis that X ...
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2answers
59 views

How can I get slope and standard error at several levels of a continuous by continuous interaction in R?

I'm comparing the slopes of several different response variables (DVs; representing different populations) to a set of predictors (IVs). For some DVs a 2-way interaction (continuous by continuous) is ...