Questions tagged [mediation]

A mediator is a variable that plays an intermediate role in a causal chain. Ie, the 1st variable in the chain causes the mediator, which in turn causes the 3rd variable. Partial mediation is when the 1st variable causes the 3rd both through the mediator & directly.

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18 views

Pathmodel fully saturated vs trimming insignificant path

I am using a pathmodel to analyze a multiple mediation. I have three exogenous variables ($x_1,x_2,x_3$) and two mediator endogenous variables ($m_1,m_2$) and one final endogenous variable that is the ...
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Mediation Package R - Does it deal with not normally distributed continuous DV and mediator variables?

I was wondering if you could help me understanding the mediation package "requirements" (by Imai and colleagues, 2019). I do not understand if the results obtained with the package are ...
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If the mediator changes the relationship between the IV and DV is it still mediation?

I found a very old question here - Mediator reverses direction of causal variable. How to interpret?, but it isn't answered. I am having almost the same issue as @jsd. I've run mediation following ...
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Mediation analysis with more than one predictor

I conducted a mediation analysis with 6 predictors, one mediator and one outcome variable. Now I am trying to write up the results but I am not quite sure how to structure my report... (e.g.: write ...
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mediation in R - impossible proportion mediated values, output interpretation

I am using the mediation package in R and would appreciate assistance with several questions. One path (let's call this the first model) involves a dichotomous predictor -> continuous mediator ->...
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Mediation in R Package lavaan: Total effect of the IV has a different p-value than the same variable in a Multiple Regression

i am really confused with the results of my mediation analysis using lavaan. I am using one predictor and several covariates. Is there any reason why lavaan could give me "wrong" p-values? ...
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19 views

How to correctly understand PROCESS model 4 for output “ Test of X by M interaction?

Perhaps some one can help me interpret some of the outputs of Hayes model 4. I designed a questionnaire that had good Cronbach and KMO scores etc. I did the PCA and have four components (factors). I ...
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8 views

Mediation package error message with group level mediator (bug?)

I am trying to use the mediation package with multilevel data and a group level mediator. I am getting a "groups do not match between mediator and outcome models" error message. However, I ...
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Mediation: How can the Total Indirect Effect be significant when the Indirect Effects are not?

I ran a mediation analysis with two mediators (M1 and M2) using lavaan and I am somehow confused about the results: Direct Effect: The total direct effect of X on Y is not significant. X is, however, ...
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Problems with KHB method for assessing mediation in nested logit models

I have a binary outcome Y, a key independent variable X and a possible mediator Z, plus a control variable C. In my original analysis I ran a "restricted" logit model of Y controlling for X ...
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40 views

Directionality of Mediation Effect

Is it possible to (statistically) determine the directionality of a mediation effect, i.e. $X \rightarrow M \rightarrow Y$ vs. $X \rightarrow Y \rightarrow M$ for example, or is this purely based on ...
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Moderated Mediation Insignificant C'

I am conducting a moderated mediation analysis using Hayes' Process Macro Model 7. I am having a significant index of moderated mediation, significant a path and b path and significant moderator X ...
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Direct effects significant, indirect effect not significant but total of indirect effects significant - how can I interpret this finding?

I have the following mediation analysis with X as the independent variable, Y as the dependent variable and three mediators (M1, M2, M3). An analysis of the direct relationships shows the following ...
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Mediation: Significant direct effect but non-significant total effect?

I have a mediation model wherein the total effect (x -> y) is non-significant, but the direct effect ox x->y is significant. There is no significant indirect effect (no mediation), and the IV- ...
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Mediation analysis with multiple independent/predictor variables?

I want to run a mediation analysis to look at the effect of X on Y, is this mediated by M? ...
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Control for common factors

Hi I have a question about how to control for common factors. I used people of a state as the sample to investigate a causal relation between two variables, y and x. Although there are a lot of ...
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Three groups in 2-1-1 multilevel mediation model: Dropping cases for comparisons?

I have data from a randomized controlled trial with two treatments (Group A and B), one control group (Group C) and four measurement points with two mediators and two outcomes. Mediators and outcomes ...
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Is there a logical way to decide whether to proceed with mediation analysis on the basis of your data?

I am running a study wherein there are multiple DVs (Y - objective performance on tasks tapping into multiple dimensions of a construct), 4 IVs (...
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Lavaan modification indices suggest to include in the model the correlations between variables produced by indprod, should I do it?

I am testing a moderated mediation with lavaan. I used indprod to calculate the interaction term ...
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Calculating power for a simple mediation model - Can I enter values observed from my own dataset into a Monte Carlo simulation covariance matrix?

I am going to conduct secondary data analysis. I need to figure out if the dataset has enough power for a simple mediation model. Each variable is observed and continuous from a cross-sectional study....
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Model Comparison with Regression

For a project I have to test a mediation model. I will do this with regression in R. The steps I take are the regular steps: Test if the IV has a relation with the DV (Regression) Test if the IV has ...
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17 views

Which package works for mediation analysis in R when variables are categorical?

I am assessing pregnancy data where my exposure is categorical variable (either dichotomized or ordinal), potential mediator is categorical (dichotomized or ordinal) and the outcome is also ...
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Defining my conceptual model

How can I define my conceptual model in terms of independent/dependent and moderating/mediating variables? My research topic is about anthropomorfism and how it can reduce food waste. My research is ...
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Moderated mediation has different results if run on R (rosetta) or on SPSS (PROCESS)?

I run the same moderated mediation in spss and in R. In R I run ...
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Mediation: Significant positive a and b paths but insignificant negative c and c' paths

I used PROCESS on SPSS to run a mediation analysis using 1 IV, 1 mediator and 1 DV. a and b paths were found to be positive and significant. However, both c and c' paths were negative and not ...
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Mediation Analysis for Mixed Models

I would like to conduct a mediation analysis in combination with mixed models. To create the mixed model, I used the lmer-package in R. My models look like the following: ...
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Calculating the index of moderated moderated mediation with multicategorical and dichotomous moderators

I am conducting a moderated moderated mediation analysis using Hayes' PROCESS macro for SAS. I have a multicategorical independent variable (i.e, three levels of X), a continuous mediator (M) and two ...
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30 views

Multiply beta coefficients from two different models

I have a count outcome with a heavy right skew that is modeled with a negative binomial. I have a continuous mediator that is modeled with OLS. We're attempting a method of causal mediation analyses ...
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Direct Effect insignificant in Mediation Analysis

If direct effect between dependent and independent variable in mediation analysis is insignificant then in the first, can we say that there is no mediation at all?
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Recommended books on Mediation Analysis?

I am interested in self learning Mediation Analysis. I have an MSc in Statistics, and I was wondering what would be an appropriate textbook to dig into this area. I would like something that combines ...
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Why do mediation and moderation analysis give substantively different results?

I have a study where I pair two people up and have them play a behavioral game together. I measure some change score before and after the game. I create a four-level factor variable called ...
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Causal Mediation for Survival Analysis: Help with Popular SAS Macro

I am attempting a simple mediation analysis in a Cox model using a popular SAS Macro as described by here Importantly, the description of the macro is also given at https://cdn-links.lww.com/permalink/...
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DAG: no back-door paths but background information shows a need for adjusting

I am interested in the effect of town of residence on income. Though the DAG has many arrows, it's interpretation is actually very simple: I have 6 covariates (Cov1-6), all causing mediation ...
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38 views

2-1-1 Multilevel Mediation with binary outcome

I have a 2 x 5 mixed effect design where the first factor is manipulated between-subjects and the last one is a within subject variable referring to the number of trials that each participant ...
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1answer
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Comparing alternative structural equation models x -> m -> y VS m->x->y

I'm new to SEM and I'm not sure if my way of testing mediations sounds right... ...
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126 views

Serial Mediation in R with three mediators (and covariates) using Lavaan - How do I code the model?

This is the model I'd like to code. And here's my current lavaan code, but I'm unsure if this is correct. [Note: I'm not interested in the M1*M2 relationship]: ...
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Observational study comparing 2 products with different (but overlapping) feature coverage

I have two software products $A$ and $B$ which form treatment $X$. $B$ is a new version of $A$ and in development. So $B$ does not have all the features that $A$ has. However, $B$ is designed to make ...
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How can I insert multiple profiles resulting from a LPA as mediators in a mediation analysis?

I'm currently writing my master thesis and I'm a little stuck at one step of the data analysis process. Maybe you can help me: I'm going to do a Latent Profile Analysis with 12 continuous variables in ...
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Could ANOVAs be used as a substitute for regression when doing mediation analysis?

I hope you can help me with these questions. I am developing a mediation analysis using the mediation package in R. I need to analyze the influence of perceived learning (Mediating Variable –MV-) in ...
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18 views

How to calculate variance and R squared in moderated mediation?

I am interested in calculating variance and r squared for an outcome $Y$ in a moderated mediation model as follows. In this model, all variables are continuous. $$Y=b0 + b1(x) +b2(m) + b3(x)(m)$$ $$m=...
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83 views

Index of moderated mediation significant, conditional indirect effects not significant?

I am running a moderated meditation analysis (Hayes process 7) with a multi-categorical moderator. Within the index of moderated mediation, three of the categories are significant (2,5,8). However, in ...
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1answer
59 views

Interpreting mediation analysis results: non-significant Prop.Mediated

I am confused on how to interpret results of my mediation analysis where my ACME is significant (but very low by absolute value) but ...
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1answer
80 views

Mediation even though index of moderated mediation is not significant?

I ran Hayes process macro in spss. In my results below, you'll see that indirect effects are significant on both levels of my Independent Varaible (IVAlgo), however the index of moderated mediation is ...
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1answer
30 views

Mediator or Moderator?

I am attempting to ascertain whether drug use is a moderator or a mediator in the following scenario. There is evidence to suggest neuroticism impacts academic performance and drug use may help ...
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37 views

Constraining correlations between two latent variables

I am running a multiple mediation model using SEM, where my 2 latent variables are my mediators, and my main predictor and my outcome are both exogenous variables. I have specified that my LVs are ...
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1answer
114 views

Mediation analysis (SEM): 2 mediators, insignificant direct and indirect effect and significant total effect

I ran 2 mediation models each with two mediators in R (lavaan) and am looking for help with interpretation. Model 1: Paths a1 and a2 = significant Paths b1 and b2 = not significant Path c' = ...
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26 views

Full vs. Partial mediation - drawing conclusions from null effects?

From day 1 in frequentist statistics classes, they teach you, "you can't drawn inferences from null effects". And yet isn't that exactly what we're doing when we distinguish between full and ...
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89 views

Serial mediation with 3 mediators [lavaan]

I want to implement a serial mediation with 3 mediators in R using the package lavaan. I found a code for the serial mediation with 2 mediators in a posting here: Serial Mediation with 2 mediators So ...
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How to test for inter-individual differences using JASP

I am trying to test if interindividual differences can mediate a relationship between my IV and DV. How can I do this?
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Causal mediation analysis interpretation help

The mediation analysis that I have run is as follows ; ...

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