Calculate expected value for coin flips

Last updated: October 9, 2025

Quick Overview

Given the following scenario about user conversion, calculate the the p-value.

Two Sigma
Analytics & Experimentation
Data Scientist
Two Sigma
October 9, 2025
Data Scientist
Phone Screen
Analytics & Experimentation
Medium

3

3

2,128 solved


Given the following scenario about user conversion, calculate the the p-value.

This analytics question from Two Sigma's Phone Screen tests your ability to think critically about data. The interviewer expects you to consider confounding variables, selection bias, and the difference between correlation and causation.

What the Interviewer Expects
  • Design a rigorous experiment with proper randomization and sample size calculation
  • Define primary and guardrail metrics with clear rationale
  • Address novelty effects, network effects, and interference
  • Segment results appropriately and identify heterogeneous treatment effects
  • Propose follow-up analyses when results are ambiguous
Key Topics to Cover
Novelty and primacy effects
Guardrail metrics
Metric definition and success criteria
A/B testing methodology
Simpson's paradox and ecological fallacy
Funnel analysis and cohort analysis
How to Approach This
  1. Define success metrics carefully. A good metric is measurable, actionable, and aligned with business goals.
  2. Run experiments long enough to account for novelty effects and weekly seasonality.
  3. Use funnel analysis to identify where users drop off for maximum optimization impact.
  4. Segment results by key dimensions (platform, country, user cohort) to catch hidden patterns.
  5. Consider network effects and interference between treatment and control groups.
Possible Follow-up Questions
  • How would you handle interference between treatment and control?
  • How would you handle seasonality in your experiment?
  • How would you handle an experiment where the control and treatment groups are different sizes?
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