Ellipsis in comparisons

[donthneni]

My question is when is ellipsis used and when it is not.

for eg.

I am as smart as he. (or)
I am smart as he is.

He does things as good as they do. (or)
He does things as good as they.

Which usage is correct and are there any exceptions. Really appreciate any replies in this regard.

-Thanks

[learner2007]

I would add "I am as smart as he is", or " I am as smart as him" Which is correct?