Author Archives: raquelandres75

About raquelandres75

I am an statistician/researcher who has decided to make a living by dedicating myself to help others who struggle with statistics.

Multiple Mediation in Stata

This post will show how to test a mediation model with more than one mediator using Stata. In order to illustrate it, I will build on the example I used in my simple mediation post by adding job anxiety as … Continue reading

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Mediation Analysis using Stata: one mediator

This post shows how to test simple mediation using Stata with and without the use of latent variables. Continue reading

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Mediation Analysis: an introduction

Mediation is defined in statistics as a model that tries to explain the mechanism through which an independent variable (X) influences an outcome (Y) via the intervening effect of a third variable, known as mediator or mediating variable (M). It … Continue reading

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How do I prepare my survival data to conduct analysis in Stata?

Let’s start by what is survival data. Survival data is characterized by having individuals that are observed over a period of time until an event of interest takes place, a.k.a failure. This event can be death, occurrence of a disease, … Continue reading

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Repeated Measures MANCOVA vs Repeated Measures ANCOVA

In a previous post, I wrote about the repeated measures (RM) ANCOVA, which is also commonly referred to as repeated measures MANCOVA. In this post, however, when I use the term repeated measures multivariate analysis of covariance (MANCOVA) I will … Continue reading

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How to test for moderation? (part 2)

If you have not read my previous post ‘How to test for moderation? (part 1)’ I recommend that you do it. In part 2 we are going to address how to test for moderation when both predictor (X) and moderator … Continue reading

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How to test for moderation? (part 1)

Let’s start by defining what moderation means in the context of a regression model or structural equation modeling (SEM). You have probably already tested for moderation without knowing that you were doing something that sounds so sophisticated, because moderation is … Continue reading

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Effect size: How to measure it and why is important

The effect size provides an estimate of the magnitude of change. For example, in a research study that estimates the efficacy of a new intervention to improve post surgery recovery after hip replacement, the effect size is a measure of … Continue reading

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When do I need to use a repeated measures ANOVA/MANOVA?

Before talking about this technique let’s clarify that when the name repeated measures MANOVA is used it commonly refers to a repeated measures ANOVA in the sense that there is only a single dependent variable or outcome of interest. For … Continue reading

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Pre-post data: Do I need to use repeated measures in my model?

First of all, let’s define what we mean by pre-post data. The classic pre-post design consists in having measurements for an outcome variable in two time points, usually before and after an intervention or treatment. It is common two have … Continue reading

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