Understanding Multiple Regression Analysis in Statistics
Learn how multiple regression helps predict outcomes using several variables and control for confounding factors, examining causal relationships and interactions in statistical modeling.
Understanding Multiple Regression Analysis in Statistics
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Presentation Transcript
So we know what linear regression is for • Predicting one variable with another variable • Yes, predicting • For example: Does gender (X1) significantly predict years of life (Y)? • What does significantly depend on?
Multiple Regression • While we are predicting things…what happens when you want to predict with more than one variable? • For example: does gender and familial history of heart disease predict blood cholesterol?
“Controlling For” • What is the effect of walking on BMI after controlling for age? • What is the effect of physical activity on depression after controlling for
Causal Inference • Relatedness: X is Correlated With Y • Temporal Precedence: X precedes Y in time • Non-Spuriousness: X and Y are still related after accounting for other relationships. (Bollen, 1989; Kenny, 1979; In Aitken, Aitken and West)
Statistical Questions Just like in linear regression • Is the whole model predicting a significant amount of variance in the dependent variable? • R-squared- ANOVA table • Are each of the Betas different than zero • T-tests
The Interaction • Does the effect of one variable depend on the level of another? • Does the effect of familial history of heart disease depend on the gender of the individual? • For example…maybe a family history of heart disease confers a risk of shorter lifespan for males but not females.
The Interaction • The fundamental equation: • What is going on here?