Path Analysis Made Easy

Path models are built up from basic models of moderation and/or mediation. It is common in psychology for the terms moderator and mediator to be used interchangeably. However, they are conceptually different. “In general terms, a moderator is a qualitative (e.g., sex, race class) or quantitative (e.g., level of reward) variable that affects the direction … Read more

What is Simple Regression? What is Multiple Regression? In simple regression a single dependent or criterion variable is related to a single independent variable or predictor variable. Multiple regression is an extension of simple regression in which the criterion is regressed against several potential predictors.   For example, a simple regression might be: can marital … Read more

This example illustrates the importance of clearly specifying your theory in terms of moderators and mediators. It’s taken from an advisory session with a PhD student who approached me to discuss how to test her theory. Her project was looking at the link between language deficit and self-esteem in young adults. Her hypothesis was that the effects of … Read more

The simplest mediation analysis involves a single independent variable, a dependent variable, and a hypothesized mediator. The unmediated model is represented by the direct effect of x on y, quantified as c. However, the effect of X on Y may be mediated by a process, or mediating variable M. Complete mediation is said to occur … Read more

So how do we go about doing a mediation analysis? In the next four posts I’ll take you through the main approaches to testing for a significant mediation effect. We’ll first look at the Causal Steps approach, made famous by Baron & Kenny (1986). Then we’ll look at several modern approaches for testing the significance … Read more

Let’s start by decomposing mediation into a number of causal steps as described by Baron & Kenny (1986). We’ll use our mediation model for the effects of Visual Anonymity on Group Attraction, mediated by Self-Categorization. The fist step is to show that the initial variable affects the outcome. In our model, we need to show … Read more

In the second step, we need to show that the initial, or predictor, variable affects the mediator. So we perform another simple linear regression using the mediator as if it were the outcome variable and regressing it on the predictor, which gives us an estimate of path a. In our example, path a describes the … Read more

Steps 3 and 4 are conducted simultaneously using multiple regression. Step 3 consists of regressing the outcome variable y onto both the mediator, m, and the predictor, x to provide an estimate of path b. Note: it is not sufficient just to correlate the mediator with the outcome; the mediator and the outcome may be … Read more

Statistics Training: Introduction to Path Analysis

  Statistics Training: Introduction to Path Analysis

    Statistics Training: Introduction to Path Analysis