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Investigate Homepage Experiment Without Control Group: Methods and Metrics

Last updated: Mar 29, 2026

Quick Overview

This question evaluates proficiency in causal inference for non-randomized treatments, experiment design hygiene, product-metric definition for a new module, and diagnostic segmentation for root-cause analysis.

  • hard
  • Pinterest
  • Analytics & Experimentation
  • Data Scientist

Investigate Homepage Experiment Without Control Group: Methods and Metrics

Company: Pinterest

Role: Data Scientist

Category: Analytics & Experimentation

Difficulty: hard

Interview Round: Onsite

##### Scenario Several experimentation and product-metric challenges for a social-media homepage. ##### Question An intern launched an experiment without a control group—how can you still estimate treatment impact? Compare matching versus propensity-score weighting and discuss their trade-offs. Review an existing A/B test and list common pitfalls that could bias the results. For a new horizontal home-feed module, what primary metrics would you track to judge success? Post-launch you observe homepage click-through dropping in treatment while DAU and time-spent stay flat—how would you investigate root causes and which user segments would you analyze first? ##### Hints Think causal inference, experiment design, diagnosable metrics hierarchy, segmentation by device, geography, tenure, power-users vs casual, etc.

Quick Answer: This question evaluates proficiency in causal inference for non-randomized treatments, experiment design hygiene, product-metric definition for a new module, and diagnostic segmentation for root-cause analysis.

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Pinterest logo
Pinterest
Jul 12, 2025, 6:59 PM
Data Scientist
Onsite
Analytics & Experimentation
94
0

Scenario

A social-media homepage team is running experimentation and product-metric analyses on a personalized feed. An intern accidentally launched a treatment to a user cohort without a randomized control group. You have standard event logs (user_id, timestamps), impression/click events, pre-period behavior history, device/geo/app-version, and eligibility flags.

Tasks

  1. No-control experiment: How can you still estimate treatment impact? Compare matching versus propensity-score weighting and discuss trade-offs.
  2. A/B test hygiene: Review an existing randomized A/B test and list common pitfalls that could bias the results.
  3. New module metrics: For a new horizontal home-feed module, what primary metrics would you track to judge success?
  4. Diagnostic scenario: Post-launch, you observe homepage click-through rate (CTR) dropping in treatment while DAU and time spent stay flat. How would you investigate root causes, and which user segments would you analyze first?

Hints

  • Causal inference when randomization is absent (matching, propensity scores, DiD/ITS/synthetic control).
  • Experiment design pitfalls and guardrails.
  • Metrics hierarchy: module-level, session-level, ecosystem, and health.
  • Segmentation: device, app version, geography, tenure, power vs casual users, exposure/reach to the module.

Solution

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