correlation and regression

Correlation

A statistical measure showing how two variables move together.

Pearson’s r

Measures the linear relationship between two continuous variables.

Parametric Test

Assumes data is normally distributed.

Spearman’s rho

Measures monotonic relationship between two variables.

Nonparametric nature

Useful for skewed data or nonlinear monotonic relationships.

Rank-Difference Correlation

Measures the relationship two ranked variables.

Scatterplot

A graph showing the relationship between two variables

Outlier

A data point that is much higher or lower than others.

Inflate r

Makes weak relationship appear strong

Deflate r

Hides true strong relationship

Regression

Statistical method for predicting the value of one variable (Y) based on another (X).

Multiple Regression

Uses two or more predictors to predict an outcome

Simple Linear Regression

Uses one predictor (X) to estimate an outcome (Y).