Interpret mixed results across segments from an experiment

Last updated: September 28, 2025

Quick Overview

An experiment shows conflicting results. What conclusions can you draw? What are the caveats?

Mastercard
Analytics & Experimentation
Product Manager
Mastercard
September 28, 2025
Product Manager
Technical Screen
Analytics & Experimentation
Medium

78

3

4,671 solved


An experiment shows conflicting results. What conclusions can you draw? What are the caveats?

This analytics question from Mastercard's Technical 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
Long-term vs short-term metrics
Simpson's paradox and ecological fallacy
Segmentation and heterogeneous effects
Sample size and power calculation
A/B testing methodology
Metric definition and success criteria
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 an experiment where the control and treatment groups are different sizes?
  • What if the experiment shows a positive short-term effect but you suspect a negative long-term impact?
  • How would you handle interference between treatment and control?
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