PayPal Data Scientist Interview Experience — Three Back-to-Back Onsite Rounds and a SQL Standoff

PayPal·Data Scientist·Jul 2025
Onsitemedium

Past experience, resume, explaining the role. Then they asked two case questions.

Case 1: 3-level apartment plus 1 basement — find the best way to operate the elevator.

Case 2: card risk — what will fraudsters do.

Onsite: 3 rounds back-to-back.

  1. Risk/fraud scenario. Started off talking about my past experience, then the interviewer explained that this DS role isn't mainly about modeling. He gave me two transactions and asked whether I'd accept or decline them, plus some simple risk-strategy scenario questions.
  2. The interviewer seemed to be a PM. Asked about my resume, then gave a case: a pile of data, how do you determine whether each transaction is fraud, explain unsupervised learning. The conversation wasn't very smooth because I kept not understanding what he actually wanted. He asked about a project on my resume and kept asking how I'd measure accuracy — I was thinking, isn't accuracy just one kind of metric? Or was he actually asking about evaluation metrics? I gave him a few models for the unsupervised learning part too, but he didn't seem to get it...
  3. SQL, three questions, none of them hard, but the interviewer basically gave no feedback. For the first one I wrote something like sum(column=x), and he asked me to explain it. After I explained, he said that doesn't work, you have to write a CASE statement. I didn't feel like arguing with him so I just wrote him a CASE WHEN version. Later there was another one where I put an aggregation inside the HAVING clause — he asked if that was even allowed. I told him I don't know what version of SQL you're writing, but in MySQL this works fine. Not sure if he believed me.

After that they asked a bunch more stuff about fraud. Overall the experience wasn't great — sometimes I genuinely didn't know what they were even asking. And when I asked them questions at the end, they also gave pretty vague answers.

Published

Curated and edited by PracHub

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Interview at a glance

Company
PayPal
Role
Data Scientist
Rounds
Onsite
Difficulty
medium
Interview date
Jul 2025
Questions from this interview
6 questions

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