Analysis of Variance and Covariance

Online Workshops

• On Demand Workshop: Assumptions of Linear Models
• Running Regressions and ANOVAs in SPSS GLM (Live)

Free Webinar Recordings

• Fixed and Random Factors in Mixed Models: What IS the difference?
• The 13 Steps to Running Any Statistical Model
• Effect Size Statistics

Articles at The Analysis Factor

• 3 Mistakes Data Analysts Make in Testing Assumptions in GLM
• 3 Reasons Psychology Researchers should Learn Regression
• 3 Situations when it makes sense to Categorize a Continuous Predictor in a Regression Model
• 7 Practical Guidelines for Accurate Statistical Model Building
• A Comparison of Effect Size Statistics
• About Dummy Variables in SPSS Analysis
• Actually, you can interpret some main effects in the presence of an interaction
• Analyzing Pre-Post Data with Repeated Measures or ANCOVA
• Anatomy of a Normal Probability Plot
• ANCOVA Assumptions: When Slopes are Unequal
• Approaches to Repeated Measures Data: Repeated Measures ANOVA, Marginal, and Mixed Models
• April 2013 Member Webinar: Hierarchical Regressions
• Assumptions of Linear Models are about Residuals, not the Response Variable
• Beyond Median Splits: Meaningful Cut Points
• Can Likert Scale Data ever be Continuous?
• Checking Assumptions in ANOVA and Linear Regression Models: The Distribution of Dependent Variables
• Checking the Normality Assumption for an ANOVA Model
• Concepts in Linear Regression you need to know before learning Multilevel Models
• Confusing Statistical Term #6: Factor
• Confusing Statistical Term #7: GLM
• Confusing Statistical Terms #1: The Many Names of Independent Variables
• Confusing Statistical Terms #3: Levels of a Factor in Multilevel Models Measured at a Nominal Level
• Confusing Statistical Terms #5: Covariate
• Continuous and Categorical Variables: The Trouble with Median Splits
• December 2013 Member Webinar: Interactions in ANOVA and Regression Models, Part 1
• Dummy Coding in SPSS GLM–More on Fixed Factors, Covariates, and Reference Groups, Part 1
• Dummy Coding in SPSS GLM–More on Fixed Factors, Covariates, and Reference Groups, Part 2
• February 2013 Member Webinar: Types of Regression Models and When to Use Them
• Five Advantages of Running Repeated Measures ANOVA as a Mixed Model
• Five Extensions of the General Linear Model
• GLM in SPSS: Centering a Covariate to Improve Interpretability
• Have you Wondered how using SPSS Burns Calories?
• How Simple Should a Model Be? The Case of Insignificant Controls, Interactions, and Covariance Structures
• How to Calculate Effect Size Statistics
• Interpreting (Even Tricky) Regression Coefficients – A Quiz
• Interpreting Interactions Between Two Effect-Coded Categorical Predictors
• Interpreting Interactions when Main Effects are Not Significant
• Interpreting Interactions: When the F test and the Simple Effects disagree.
• January 2014 Member Webinar: Interactions in ANOVA and Regression Models, Part 2
• January 2015 Member Webinar: ANCOVA (Analysis of Covariance)
• July 2017 Member Webinar: The Multi-Faceted World of Residuals
• June 2013 Member Webinar: MANOVA
• June 2014 Member Webinar: Multiple Comparisons
• Linear Mixed Models for Missing Data in Pre-Post Studies
• May 2013 Member Webinar: Using Excel to Graph Predicted Values from Regression Models
• Model Building Strategies: Step Up and Top Down
• New version released of Amelia II: A Program for Missing Data
• Non-parametric ANOVA in SPSS
• One-tailed and two-tailed tests
• Problems Caused by Categorizing Continuous Variables
• Six Differences Between Repeated Measures ANOVA and Linear Mixed Models
• Specifying Fixed and Random Factors in Mixed Models
• Specifying Variables as Within-Subjects Factors in Repeated Measures
• Spotlight Analysis for Interpreting Interactions
• SPSS GLM: Choosing Fixed Factors and Covariates
• Steps to Take When Your Regression (or Other Statistical) Results Just Look…Wrong
• Testing and Dropping Interaction Terms in Regression and ANOVA models
• The 13 Steps for Statistical Modeling in any Regression or ANOVA
• The 3 Stages of Mastering Statistical Analysis
• The Assumptions of Linear Models: Explicit and Implicit
• The Difference Between Clustered, Longitudinal, and Repeated Measures Data
• The Difference Between Crossed and Nested Factors
• The Difference Between Eta Squared and Partial Eta Squared
• The Difference Between Interaction and Association
• The General Linear Model, Analysis of Covariance, and How ANOVA and Linear Regression Really are the Same Model Wearing Different Clothes
• The Problem with Using Tests for Statistical Assumptions
• The Repeated and Random Statements in Mixed Models for Repeated Measures
• The Wide and Long Data Format for Repeated Measures Data
• Using Adjusted Means to Interpret Moderators in Analysis of Covariance
• What Is Regression to the Mean?
• What’s in a Name? Moderation and Interaction, Independent and Predictor Variables
• When Assumptions of ANCOVA are Irrelevant
• When Dependent Variables Are Not Fit for Linear Models, Now What?
• When Does Repeated Measures ANOVA not work for Repeated Measures Data?
• When Dummy Codes are Backwards, Your Stat Software may be Messing With You
• When to Check Model Assumptions
• When to leave insignificant effects in a model
• When Unequal Sample Sizes Are and Are NOT a Problem in ANOVA
• Why ANOVA and Linear Regression are the Same Analysis
• Why ANOVA is Really a Linear Regression, Despite the Difference in Notation
• Why report estimated marginal means in SPSS GLM?