PSYC3010 – Mediation & Indirect Effects Lecture

A comprehensive set of question-and-answer flashcards covering key definitions, paths, statistical tests, examples, assumptions, and advanced topics related to mediation and indirect effects as presented in the PSYC3010 lecture.

What does a mediation model seek to explain in regression?

How a predictor (X) exerts an indirect effect on a criterion (Y) through a mediator (M).

In mediation terminology, what is an "indirect effect"?

The influence of X on Y that is transmitted through the mediator M (X → M → Y).

According to Baron & Kenny (1986), what is Path A?

The relationship between the predictor and the mediator (X → M).

According to Baron & Kenny (1986), what is Path C (the total effect)?

The relationship between predictor and criterion before the mediator is entered (X → Y).

What is Path B in traditional mediation analysis?

The relationship between the mediator and the criterion controlling for the predictor (M → Y | X).

What is Path C′ (C-prime) in mediation?

The direct effect of X on Y after M is controlled (X → Y | M).

Which statistical test traditionally evaluates the significance of the indirect effect?

The Sobel Test.

What modern resampling method is often preferred over the Sobel Test for indirect effects?

Bootstrapping (typically 5,000–10,000 resamples).

State the four classic Baron & Kenny conditions for declaring mediation.

(1) Path A significant. (2) Total effect (C) significant. (3) Path B significant. (4) Direct effect (C′) weaker than C, and indirect effect significant.

How does ‘partial mediation’ differ from ‘full mediation’?

In partial mediation, C′ remains significant; in full mediation, C′ is no longer significant once M is included.

What three conditions are considered sufficient in contemporary mediation approaches (e.g., Hayes)?

Significant Path A, significant Path B, and significant indirect effect (X → M → Y).

Which SPSS procedure tests Path A in simple mediation?

A bivariate regression of M on X.

Which SPSS procedure tests Paths C, B, and C′ simultaneously?

A hierarchical multiple regression entering X at Step 1 and M at Step 2 predicting Y.

What does a 95 % bootstrapped confidence interval that excludes zero indicate?

The indirect effect is statistically significant.

In the exercise–self-esteem–happiness example, what served as the mediator?

Self-esteem.

What was the main finding of the Sobel Test in the exercise example?

Exercise had a significant indirect effect on happiness through self-esteem (p ≈ .046).

Define a suppressor variable in regression.

A variable that, when controlled, increases the magnitude of the relationship between a predictor and criterion.

How can a suppressor effect mask a theoretically positive X–Y relation?

Opposing indirect pathways (e.g., X → M → Y negative) cancel out the positive direct effect until M is controlled.

Give an everyday suppressor example mentioned in the lecture.

Conscientiousness positively predicts achievement, but performance anxiety (a negative mediator) can suppress this link.

Differentiate mediation from moderation in one sentence.

Mediation explains how or why X affects Y, whereas moderation indicates when or for whom X affects Y (changes the strength of X–Y).

Does a moderator (W) need to correlate with the predictor (X)?

No, there is no requirement for X–W association in moderation.

What graphical test is typically used to probe moderation but not mediation?

Simple slopes analysis of X on Y at low and high levels of W.

Name two complex extensions of simple mediation covered in the lecture.

Multiple mediation and sequential (serial) mediation.

What analytic family encompasses multiple, serial, and parallel mediations?

Path analysis.

How does structural equation modeling (SEM) extend path analysis?

By using latent variables measured by multiple indicators to account for measurement error.

List the five key assumptions of multiple regression reviewed.

Linearity, normality of errors, homoscedasticity, independence of errors, and lack of multicollinearity.

What is homoscedasticity?

Equal variance of residuals across all levels of the predicted values (Ŷ).

Why can’t simple survey-based mediation establish true causality?

Because variables are not experimentally manipulated; alternative causal orders or third variables may explain associations.

What experimental design helps strengthen causal claims in mediation?

An experimental-causal-chain design manipulating X in Study 1 and M in Study 2.

In the exercise example, which regression step tested the total effect?

Step 1 of the hierarchical regression (X predicting Y alone).

What happens to the X coefficient from Step 1 to Step 2 if partial mediation exists?

It decreases but remains significant.

What value did the bootstrapped indirect effect (IE) have in the example?

IE = .15 with 95 % CI [.03, .34].

Why is multicollinearity problematic in regression?

Highly correlated predictors inflate standard errors, making it hard to isolate individual predictor effects.

Which assumption ensures residuals do not display systematic clustering?

Independence of errors.

What statistical symbol is commonly used for unstandardised regression slopes?

b.

What symbol denotes standardised regression coefficients?

β (beta).

In mediation figures, what does asterisks beside path coefficients denote?

Levels of statistical significance (*p < .05, **p < .01, ***p < .001).

Name two reasons statisticians critique the strict Baron & Kenny steps.

(1) Total effect (C) may be unnecessary; (2) suppressor effects or distal mediators can yield meaningful mediation even when C is non-significant.

What sample size issue often plagues the Sobel Test?

It assumes normality of the indirect effect and can be under-powered in small samples.

How many participants were in the example exercise study?

30 participants.

Which correlation is required to begin testing mediation?

A significant correlation between predictor (X) and mediator (M).

What does Path C′ being “weaker than Path C” indicate?

The mediator accounts for part of the X–Y relationship (evidence of mediation).

Give an example of a positive mediator pathway for social media use → happiness discussed in class.

Increased social connection or social support (open-ended answer acceptable for students).

Give an example of a negative mediator pathway for social media use → happiness.

Upward social comparison leading to lower self-esteem (open-ended answer acceptable).

Why must we report either b or β consistently across paths in mediation?

To maintain interpretational consistency and allow comparison across paths.

What regression output section provides R² changes when adding the mediator?

Model Summary (Change Statistics) in hierarchical regression.

Under what circumstance might mediation be claimed even if X–Y is non-significant?

When indirect effects are significant but opposing pathways suppress the direct relationship.

What is the practical implication of suppressor effects for researchers?

They highlight the need to measure multiple mediators to uncover hidden mechanisms.

What two lecture periods are there no PSYC3010 classes according to the schedule?

Week 3 (no lecture/tutorials) and Week 10 (Labour Day break).

Which statistical program was used throughout the tutorial demonstrations?

SPSS.

Why are partial and semi-partial correlations usually omitted in basic mediation output?

Because mediation interpretation focuses on regression coefficients (b or β), not unique variance partitions.

What does ‘complex mediation’ allow researchers to do beyond simple mediation?

Test multiple mediators simultaneously and compare their indirect effects.

What is the ultimate goal of including figures when reporting mediation?

To visually depict the mediation model with path coefficients for clarity.

What should you do if the regression assumptions are violated?

Consider data transformations, different analytic techniques, or address outliers to satisfy assumptions.

Where can students post PSYC3010 questions outside class time?

On the course Padlet or via the lecturer’s email.