## Applied Statistics Lesson of the Day – Polynomial Regression is Actually Just Linear Regression

June 19, 2014 Leave a comment

Continuing from my previous Statistics Lesson of the Day on what “linear” really means in “linear regression”, I want to highlight a common example involving this nomenclature that can mislead non-statisticians. **Polynomial regression** is a commonly used multiple regression technique; it models the systematic component of the regression model as a -order polynomial relationship between the response variable and the explanatory variable .

However, **this model is still a linear regression model**, because the *response variable is still a linear combination of the regression coefficients*. The **regression coefficients** would still be estimated using **linear algebra** through the **method of least squares**.

Remember: the “linear” in linear regression refers to the linearity between the response variable and the regression coefficients, ** NOT** between the response variable and the explanatory variable(s).

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