How to check if the regression model fits the data well?

How to check if the regression model fits the data well?



R squared/Adjusted R squared:
- R2=RSStot−RSSresRSStot=RSSregRSStot=1−RSSresRSStotR2=RSStot−RSSresRSStot=RSSregRSStot=1−RSSresRSStot
- Describes the percentage of the total variation described by the model
- R2R2 always increases when adding new variables: adjusted R2R2 incorporates the model's degrees of freedom

F test:
- Evaluate the hypothesis HoHo: all regression coefficients are equal to zero Vs H1H1: at least one doesn't
- Indicates that R2R2 is reliable

RMSE:
- Absolute measure of fit (whereas R2R2 is a relative measure of fit)

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