Data Scientist Interview Questions | Glassdoor

Data Scientist Interview Questions

"Every business collects data, and it's the job of the data scientist to analyze, interpret, and communicate that information in a way that will help drive company decisions. In an interview, expect to answer technical questions about your ability to perform quantitative tests as well as create clear visualizations of large, complex data sets. Come ready to discuss past projects you've worked on and how you communicate data findings clearly and concisely in order to help solve business-related problems."

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You are compiling a report for user content uploaded every month and notice a spike in uploads in October. In particular, a spike in picture uploads. What might you think is the cause of this, and how would you test it?

3 Answers

Hypothesis: the photos are Halloween pictures. Test: look at upload trends in countries that do not observe Halloween as a sort of counter-factual analysis.

We cannot say what has caused the spike since causal relationship cannot be established with observed data. But we can compare the averages of all the months by performing a hypothesis testing and rejecting the null hypothesis if the F1 score is significant.

The photos are definitely Halloween pictures. Segment by country and date and check for a continual rise in photo uploads leading up to October 31st and a few days after for the lag. There's also a ton of these product questions like this on InterviewQuery.com for data scientists

How do you take millions of users with 100's of transactions each, amongst 10k's of products and group the users together in a meaningful segments?

3 Answers

Find the second largest element in a Binary Search Tree

16 Answers

How would you test if survey responses were filled at random by certain individuals, as opposed to truthful selections?

5 Answers

How would you build and test a metric to compare two user's ranked lists of movie/tv show preferences?

3 Answers

The three data structure questions are: 1. the difference between linked list and array; 2. the difference between stack and queue; 3. describe hash table.

1 Answer

You're about to get on a plane to Seattle. You want to know if you should bring an umbrella. You call 3 random friends of yours who live there and ask each independently if it's raining. Each of your friends has a 2/3 chance of telling you the truth and a 1/3 chance of messing with you by lying. All 3 friends tell you that "Yes" it is raining. What is the probability that it's actually raining in Seattle?

37 Answers

Write a SQL query to compute a frequency table of a certain attribute involving two joins. What if you want to GROUP or ORDER BY some attribute? What changes would you need to make? How would you account for NULLs?

25 Answers

Given an list A of objects and another list B which is identical to A except that one element is removed, find that removed element.

20 Answers

Consider a game with 2 players, A and B. Player A has 8 stones, player B has 6. Game proceeds as follows. First, A rolls a fair 6-sided die, and the number on the die determines how many stones A takes over from B. Next, B rolls the same die, and the exact same thing happens in reverse. This concludes the round. Whoever has more stones at the end of the round wins and the game is over. If players end up with equal # of stones at the end of the round, it is a tie and another round ensues. What is the probability that B wins in 1, 2, ..., n rounds?

19 Answers
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