In my textbook, the following results are proved in the context of SIMPLE linear regression:

∑e_i = 0

∑(e_i)(Y_i hat)= 0

I tried to modify the proofs to mutliple linear regression, but I am unable to do so, so I am puzzled...

Are these results also true inMULTIPLElinear regression?

Thanks!

[also under discussion in Talk Stats forum]