Assume you need to generate a predictive model using multiple regression. Explain how you intend to validate this model?
Validation using R2R2: % of variance retained by the model Issue: R2R2 is always increased when adding variables R2=RSStot−RSSresRSStot=RSSregRSStot=1−RSSresRSStotR2=RSStot−RSSresRSStot=RSSregRSStot=1−RSSresRSStot Analysis of residuals: Heteroskedasticity (relation between the variance of the model errors and the size of an independent variable's observations). Scatter plots residuals Vs predictors. Normality of errors Etc. : diagnostic plots Out-of-sample evaluation: with cross-validation .