When are OLS estimators BLUE?

already exists.

Would you like to merge this question into it?

already exists as an alternate of this question.

Would you like to make it the primary and merge this question into it?

exists and is an alternate of .

For Classical Regression Model the OLS or Ordinary Least Squares - estimators (or the betas) are BLUE (Best, Linear, Unbiased, Estimator) when :
  1. The regression is linear in the coefficients, it is correctly specified and has an additive error term.
  2. Mean of the error term is zero. (Include a constant term in the regression (B0 which will force the mean to be zero)
  3. The independent variables are not correlated with the error term. (If they are correlated then the betas will be biased.)
  4. Observations of the error term (the residuals) are not correlated with each other.
  5. The error term has a constant variance (Homoskedasticity)
  6. No independent variable is a perfect linear function of any of the other independent variable. (If this is true - multicollinearity will occur)
38 people found this useful

Who is ol' blue eyes?

Frank Sinatra ---------------- See http://en.wikipedia.org/wiki/Frank_Sinatra

Who is ol blue eyes?

Frank Sinatra ------------ See http://en.wikipedia.org/wiki/Frank_Sinatra

What is the estimation of Blue Whales?

A rough estimation is in low few thousands. This is because their were hunted and classed as endangered by 1950s. The pre-whaling population is estimated to be around 350,000