Calculate variance for user retention

Last updated: November 21, 2025

Quick Overview

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

Mastercard
Analytics & Experimentation
Product Manager
Mastercard
November 21, 2025
Product Manager
Take-home Project
Analytics & Experimentation
Medium

29

3

4,905 solved


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

Analytics questions at Mastercard evaluate your ability to define metrics, design experiments, and derive actionable insights from data. This Take-home Project question tests your end-to-end analytical thinking.

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
Segmentation and heterogeneous effects
Sample size and power calculation
Simpson's paradox and ecological fallacy
Guardrail metrics
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
  • What if you discover a bug in the logging during the experiment?
  • What if the experiment shows a positive short-term effect but you suspect a negative long-term impact?
  • How would you handle an experiment where the control and treatment groups are different sizes?
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