Omitted variable bias, long and short regression

[@derknipser8386]

How can you put the ß^lr_1 and ß_2out of the cov(...) term in the 4th line? How do you know that the cov(x_1i,ß_0) is equal to 0?

[@sebastians.poshteh6877]

1. ß^lr_1 and ß_2out of the cov(...) --> Cov(X, aY) = aCov(X,Y) for "a" as a constant. This can be applied to ß^lr_1 and ß_2 in the 4th line. 2. Cov(x_1i,ß_0) is equal to 0: as the Cov(x,a) is equal to 0. In this case, we have ß_0 as a constant.

[@derknipser8386]

@@sebastians.poshteh6877 Thank you