He is THE BEST TA I've ever had at Columbia. Seriously.
Since I was not sure whether I should major in Econ or not, metrics was a challenging subject for me. But his recitation and OH made it possible for me to get a solid A. It's simeple. you go his rec, you get A. It's guaranteed.
When I was having hard time on dummy variable, he patiently explained it over and over again, so that I could nail the exams and homeworks.
And the best thing about him is his grading is very fair and flexible.
He knows that this is not the only course you are taking.
I hope I can take more courses that he is TAing.
Seriously the best TA you can ever ask for.