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

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2
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1answer
17 views

How to decide which main variable is modified by the interaction term?

Given the following linear model $Y=int+aX1+bX2+c(X1*X2)+e$, where $X1$ and $X2$ are the main variables, ($X1*X2$) is the interaction term, and $a$, $b$, and $c$ are the corresponding coefficients. ...
-1
votes
0answers
19 views

The results of the univariate analysis differ from the resuls of the multivariate analysis. [on hold]

when i test the effect of an Independent variable on the dependent variable ( using stata 12) without entering the other independant variables in the regression, i found the same results as the ...
0
votes
0answers
14 views

Best procedure for evaluating group differences in a Lasso regularized regression

I am evaluating 25 predictors (continuous, ordinal, multinomial) on an ordinal outcome variable using a lasso regularized regression. I am using the lasso for variable selection, to determine which ...
0
votes
0answers
5 views

interaction term in ordinal probit model

I am working on an ordinal probit model. If i plan to introduce an interaction term between a dummy variable and an ordinal variable (having 3 and in some cases 5 categories) , then is such an ...
2
votes
1answer
22 views

Adjusted R-squared: number of terms or independent variables?

When applying a multiple linear regression, does the adjusted R-squared value depend on the number of independent variables in the model or the number of terms? Specifically, I'm concerned that adding ...
1
vote
2answers
42 views

main effect in logistic regression with the presence of interaction

I just have a question about how to get the main effect in the presence of interaction effect. I have two cohort: say cohort A and cohort B . For cohort A, I have this code as 1. Zero for cohort B. ...
1
vote
1answer
16 views

Continuous vs. categorical variables in interaction terms

My analysis includes, among others, three independent variables: X (interest rate), Y (type of rate; it is a dummy), and Z (likelihood of bankruptcy). I have transformed the latter into a categorical ...
0
votes
0answers
28 views

Multiple regression with categorical moderator (age) and continuous IV's and DV

I am doing a multiple regression with 6 IV's, 1 DV, and 1 moderator. I am having a problem trying to understand how to get the effect of the moderator which is age group (i.e. 18-25, 26-35, etc.). ...
0
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0answers
24 views

Two-way ANOVA: negative interaction sum of squares?

I am doing a two-way ANOVA. The two variables are both categorical, one with 3 and the other with 2 categories. The count for each category is not equal. The data (only category means) is here: ...
1
vote
1answer
32 views

Multicollinearity and interaction terms

My dataset has 2734 observations (but in some speficitations, that number reduces to 1280). I also have interaction terms (in some specifications, even fourth-order terms). As far as I know, ...
0
votes
0answers
11 views

effect of modifiers- case crossover

I am studying the effect of air pollution (PM) on health outcomes, and the characteristics that might modify this effect, using the case crossover analysis based on the conditional logistic ...
0
votes
1answer
31 views

How to interpret interaction between a dummy and a continuous variables in ols?

I am trying to examine the association between maternal education and child school test scores using the following equation. $$\small{TestScore_i = \beta_0 + \beta_1 EduYrMom_i + \beta_2 ...
0
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0answers
12 views

Sketching of Graph following Moderated Regression

I'm new to moderated regression and this site and I have a question on deriving the regression equation to sketch the slopes required for interpreting of a moderated regression. All of the other sites ...
0
votes
0answers
12 views

interaction term not in expected direction

I am conducting a hierarchical regression analysis to test interaction effects. The main variable and the moderator are related to the dependent variable significantly and in expected direction. ...
1
vote
1answer
54 views

Compare linear models with and without an interaction effect

I want to compare the following two linear models: model 1: y = mean + A + B model 2: y = mean + A + A*B Is model 2 equivalent to y = mean + A + B + A*B? Can I ...
1
vote
0answers
29 views

How to determine the significance of an interaction?

My question is simple: How do you determine the overall significance of an interaction (i.e. the marginal effect of $X$ on $Y$ for different values of $Z$)? But the background is a bit ...
3
votes
1answer
73 views

Can you determine if an interaction exists from a correlation matrix?

Below are the results of a correlational analysis. This table shows the correlations among 8 variables (performance expectancy, ...
3
votes
2answers
58 views

Predicting an output based on whether a variable is above or below a threshold

I want to create a linear regression model to predict an output that uses two different coefficients based on some threshold within the data. For example: df: ...
1
vote
0answers
22 views

Running 2x2x2 ANCOVA in SPSS

I need to conduct an ANCOVA on my data. While I've taken a number of statistics courses, I have never come across ANCOVAs and I want to get some feedback on the correct way to conduct this analysis. ...
0
votes
1answer
31 views

GAMLSS: model with interaction terms failed

I use gamlss method from library(gamlss) on my full models with interaction terms and try to reduce them with stepGAIC. There are 3 things I want to ask. Do I have to specify a link for the model? ...
0
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0answers
6 views

how to analyse an interaction in a within-subjects repeated ANCOVA post-hoc?

I have pre and post measures of attention that I am examining in a within-subjects repeated measures design. I wanted to check the effect of verbal intelligence [VIQ] on my attention[pre/post] ...
0
votes
0answers
3 views

How to interpret/detect interactions with proportional effects

Assume I have an experiment with 2X2 factors. Let's name the first factor F1 with the levels ...
3
votes
2answers
75 views

How to deal with values that don't exist, as opposed to are missing?

I am working with a dataset where the dependent variable is $y$ (level of use of a line of credit) and the key independent variables are $x_1$ and $x_2$ (two different types of interest rates). Some ...
2
votes
1answer
44 views

How does step function selects best linear Models which includes polynomial effects and interaction effects in R?

I try to find "best" linear models with continuous and categorical covariables with Interaction Effect by BIC. The continuous covariables should have a quadratic effect on the response variable. ...
0
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0answers
6 views

SPSS Multinomial Logistic Regression Interaction Term Reference [migrated]

I am building a multinomial logistic regression model in SPSS. The dependent variable has 4 levels. There are two categorical factors; one factor has 4 levels, the other factor has 5 levels. I am also ...
1
vote
1answer
73 views

Plot regression with interaction in R

I did a regression analysis with the following variables: Predictor = dummy variable, dependent Variable = metric, moderator variable = metric. I now want to show my results in a figure. The ...
0
votes
0answers
28 views

minitab p-values of interactions

I am having some trouble in Minitab. I constructed a L16 Taguchi orthogonal array for 5 factors which all have 2 levels by using Minitab, and I need to check if all the interactions are significant or ...
5
votes
4answers
227 views

Nonlinear effect in an interaction term

If you have B, which is a 0/1 outcome variable, S, which is a continuous variable, and ...
0
votes
1answer
43 views

Mean separation when interaction is significant

I am analyzing a factorial experiment in RCBD (3 cultivars x 4 inoculation methods with 10 replicates). All main effects and interactions are significant for a particular response variable. But in ...
3
votes
2answers
115 views

Does triple interaction need to include all main effect variables?

I have a triple interaction: AxBxD, where A and B are continuous variables and D is a dummy. My regression is Y = A + B + AxB + AxD + AxBxD In this case, do I HAVE TO include BxD also? In theory here ...
1
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0answers
17 views

Can dependent variables appear in interaction terms in a system of simultaneous equations?

Given a system of 2 equations with y1 and y2 the dependent variables: \begin{align} y1 &= a0 + a1x1 + a2(x2y2) + ... + e1 \tag 1 \\ y2 &= b0 + b1x1 + b2(x2y1) + ... + e2, \tag 2 \end{align} ...
1
vote
1answer
63 views

dummy variables, interaction with continuous variable, and variable selection

I want to predict shop sales from a set of independent variables which consists of shop attributes like floor space, no. of stuff of a specific store (continuous variables) and also location of the ...
1
vote
1answer
42 views

Can site be used as a factor in a multiple regression model?

I am studying two sites with different fertility and soil texture. In the model I used the data from both sites. I would like to know if could I could use the site as a factor (variable) in the model? ...
1
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0answers
9 views

interpreting Interaction 3 way interaction [duplicate]

What is the simplest way to understand three-way interactions? My interaction was negative and main effect was negative. Other interaction was negative and main effect was positive.
0
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0answers
24 views

Model-selection and interactions: Glmnet dropping underlying terms

I have a dataset and want to do an Ancova with several explanatory variables (several factors and two covariates) and their interactions. I want to select the best model using glmnet and lasso ...
4
votes
1answer
50 views

Account for multiple treatments to the same subject when the treatments are a numerical variable

254 individuals were asked their purchase intent of a product (on a 1-5 scaled) at different prices \$699, \$799, \$899, \$999, and \$1099. The data looks like: ...
2
votes
1answer
52 views

Is it better to remove higher order interactions or least significant terms first in model simplification?

I have a mixed effects model with 3 explanatory factors and a full interaction set (including 3 way interaction). This is the full model. Factor 1 is time and I am interested in the change in the ...
2
votes
1answer
110 views

three-way-interaction between two continuous and one binary variable using OLS stata

I'm facing difficulties in interpreting a three-way-interaction term. I'm using OLS and the three-way-interaction term is significant. Y is the response variable (continuous), X the predictor ...
0
votes
0answers
32 views

Two basic questions on hierarchical/multilevel modeling re: specific term interpretation and when to use in general

Suppose a hierarchical model with varying intercepts and varying slopes, with a single individual-level predictor $x$ and a single cluster-level predictor $z$. After inserting the level 2 equations ...
0
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0answers
53 views

To use Interactions or to split the sample?

I have panel data for 16 years and 134 countries. I am using fixed effects model and using following regression models: Model 1: $y = \beta_0 + \beta_1 X_1 + \beta_2 X_2 + \epsilon $ Model 2: $y ...
3
votes
1answer
65 views

Kruskal-Wallis and Ordinal Logistic Regression

Many relate Ordinal Logistic Regression (OLR) with Kruskal-Wallis (KW) in the sense that OLR may be used when there are two or more IVs and interaction effect between them are of interest, while KW ...
1
vote
1answer
25 views

Interactions - using ratio of variables

I have 3 variables, colony size, colony age and growth rate (colony size/age). I am interested to predict various other properties ($y$) of a colony using these 3 variables; $y = a_1 \text{ size} + ...
1
vote
1answer
79 views

Curvilinear relationship with moderator

I am trying to moderate a curve and determine which equation I should follow. A simple curvilinear relationship has the following equation: (1) $Y = b_0 + b_1X + b_2X^2$ (i.e. a linear term and a ...
2
votes
2answers
44 views

Imputing using CFA for use in a Cox regression

I am using CFA (confirmatory factor analysis) to create a measurement model of social capital that is to be used in a Cox regression. Because of missing data I first impute the incomplete data by MICE ...
0
votes
0answers
12 views

Performing interaction with a very significant predictor drives down p val of other predictors. But does it makes sense?

I'm observing a phenomenon that I can't understand. I have a linear regression setting with categorical vars. A couple of these elicit an highly significant coefficient and low p values. When used ...
0
votes
0answers
53 views

PROCESS (Hayes) by using IV categorical

I am trying to run a moderation using SPSS with Hayes'macro. But I have a IV with 3 categories (a,b,c). In his page Hayes gives this explanation (see below) but I am not sure how to do this using ...
2
votes
1answer
17 views

What's the best way to model two insurance categories that are non-exclusive?

I am modeling insurance status in a logistic regression as separate dummy variables for private, Medicare, Medicaid, uninsured, etc. For people that are dual eligible, should I have a separate "dual ...
1
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0answers
15 views

How to analyze the interaction of temperature and PM on mortailtiy? [closed]

library(dlnm);library(mgcv);library(splines);library(tsModel) the model for main effect,(R code) ...
2
votes
2answers
29 views

Can a continuous effect modifier be categorized into quartiles? [duplicate]

Is it statistically sound to dummy code a continuous variable (effect modifier) into quartiles and compare the odds ratios of an IV vs. DV in Q1 and IV vs. DV in Q4 in logistic regression? If so, how ...
0
votes
1answer
46 views

Multi level regression with interaction using R lme4

I'd like to do a regression analysis with interactions, my data has two levels (school classes and pupils). My variables are: Predictor = dummy variable on Level 1, dependent Variable = metric on ...