It is just like everyone else said. They will send you a takehome test involving two exercises: one is a coding exercise and one is about optimizing passenger pick up. The coding exercise was very simple, which makes me believe that at uber data scientists have nothing to do with production code. The pick up exercise was open ended and Uber was also very vague in terms of how detailed the answer should have been, how much time I should have spent on it, etc. I failed that so I didn't go to the following round. My main complaint is that when they send you a takehome test they should set expectations clearly on whether they just want to see how you would tackle the problem or they want a detailed 10 page report!