Point72 Data Scientist Interview Experience — HackerRank OA Then a Decision-Tree Phone Screen

OA

60 minutes, 4 questions on HackerRank. Same as most experience reports here, except the third question was SQL — for the others you could pick Python or R. But I'd guess most people here just use Python.

1. Date transformation
2. Arbitrary shopping (screenshot attached)
3. SQL question (pretty easy)
4. Given the centers and radii of two circles, write a function to determine their positional relationship

My performance: I only got questions 3 and 4 fully correct. The first question had some case that inexplicably wouldn't pass, and the second question failed a bunch of cases.

Result: a few days later I got a DS phone interview.

DS Phone Interview

Back-to-back, half an hour each. They asked about my internship experience — I had worked on a decision tree, so they latched onto that: explain a decision tree, (they wanted to ask about random forest but I said I hadn't used it, so they dropped it), did I try other methods, why did I choose this method, if I had the chance what else would I try, how do you know you're not overfitting, how do you choose tree depth.

They also asked how big the internship dataset was and how many features it had.

They also asked a probability question: you have one dollar, and you flip a fair coin. If it's heads, the money doubles; if it's tails, you take whatever you have at that point and the game ends. For example, first flip heads — it becomes two dollars; another heads — it becomes four dollars; another tails — the game ends, and you take the four dollars. How much would you pay to play this game? (That should be roughly the question — it's an expected-value problem anyway, and other people here have mentioned something similar.)