Mastering Microsoft’s Data Scientist Interview: A Deep Dive into AB Testing & Metrics

Software Engineering
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microsoft | Data Scientist | Interview Experience

Interview Date: Not specified
Result: Not specified
Difficulty: Not specified

Interview Process

The interview consisted of four rounds. Each round began with the candidate discussing a project for about 20 minutes, followed by deep dive questions based on what the candidate mentioned.

First Round:

  • Discussed A/B testing process and how to ensure both groups have similar characteristics.
  • Questions included how to conduct an A/A test and how to handle multiple metrics using Bonferroni correction or FDR correction.
  • Asked about determining sample size and explaining p-value.
  • A statistics question involving two coins: one flipped 100 times resulting in 47 heads, and another flipped 1000 times resulting in 480 heads. The candidate was asked which coin is more unfair.
  • A coding question to merge two sorted lists.

Second Round:

  • Discussed a machine learning case about preventing a drop in ad revenue. The candidate initially misinterpreted the question as a case study rather than focusing on predictive models.
  • The interviewer asked about considering microeconomic factors, which the candidate struggled to address.
  • A probability calculation coding question involving three bags of balls, where the candidate had to determine the probability of drawing from a specific bag after drawing a red ball.

Third Round:

  • A case study on identifying the root cause of a 5% drop in ad revenue and how to summarize findings. The candidate struggled with quantifying the drop and reporting effectively.
  • Another question related to constructing an airport and considering various features, but the candidate did not focus on the key aspects.

Fourth Round:

  • The manager asked about a secondary business project involving an NLP model for matching. The candidate could not adequately explain the matching process.
  • A behavioral question about conflict resolution and a simple statistics question related to Bayes’ theorem. The interview concluded 25 minutes early.

Technical Questions

  1. Two Sum (Coding)
  2. Merging two sorted lists (Coding)
  3. A/B testing process (Statistics)
  4. Probability calculation involving Bayes’ theorem (Statistics)

Tips & Insights

  • Be prepared to clearly explain the A/B testing process and statistical concepts.
  • Familiarize yourself with microeconomic factors that may influence business decisions.
  • Practice articulating your thought process when discussing case studies and root cause analysis.
  • Review probability and statistics, especially Bayes’ theorem, as it may come up in technical questions.