171 Weighted least squares

This video explains weighted least squares (WLS) as a powerful econometric technique that addresses heteroscedasticity, a common issue where the variance of the error term is not constant. Unlike Ordinary Least Squares (OLS), which gives equal weight to all observations, WLS assigns higher weights to more precise observations and lower weights to noisy ones, leading to more efficient and reliable estimates. The video details how WLS works by minimizing a weighted sum of squared residuals and contrasts its benefits with robust standard errors, highlighting its theoretical advantage as the best linear unbiased estimator when weights are correctly specified. It also discusses the practical challenges of accurately estimating these weights and when robust standard errors might be a more suitable alternative in applied econometrics. Visit AxiomTutoring.com and subscribe to @AxiomTutoringCourses.