Least

Questions on Weighted Least Square Estimation

Questions on Weighted Least Square Estimation
  1. How do you choose weights for weighted least squares?
  2. Is WLS more efficient than OLS?
  3. When should I use weighted least squares?
  4. What is weighted least square method?

How do you choose weights for weighted least squares?

Weighted least squares (WLS) regression is not a transformed model. Instead, you are simply treating each observation as more or less informative about the underlying relationship between X and Y. Those points that are more informative are given more 'weight', and those that are less informative are given less weight.

Is WLS more efficient than OLS?

The use of WLS may be justified if you believe that different observations have different error variances, i.e. Var(ε1)=… =Var(εn) does not hold. Then WLS may be more efficient than OLS (as long as you are able to obtain weights that are roughly proportional to inverse error variances).

When should I use weighted least squares?

If the standard deviation of the random errors in the data is not constant across all levels of the explanatory variables, using weighted least squares with weights that are inversely proportional to the variance at each level of the explanatory variables yields the most precise parameter estimates possible.

What is weighted least square method?

Weighted least squares (WLS), also known as weighted linear regression, is a generalization of ordinary least squares and linear regression in which knowledge of the variance of observations is incorporated into the regression. WLS is also a specialization of generalized least squares.

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