Variance with Heteroskedasticity For the general multiple regression model, a valid estimator of VarlB, with heterosked asticity is ∑ SsT2, Where r, is the i residual from regressing x, on all other independen t variable S, and SST, is the sum of squared residuals from this regression Economics 20- Prof anderson 6Economics 20 - Prof. Anderson 6 Variance with Heteroskedasticity ( ) ( ) is the sum of squared residuals from this regression regressing on all other independen t variable s, and , where ˆ is the residual from ˆ ˆ ˆ ˆ with heterosked asticity is ˆ estimator of For the general multiple regression model, a valid t h 2 2 j j i j j i j i j j SST x r i SST r u V ar Var b =  b