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Analyze an A/B test and present recommendation

Last updated: Mar 29, 2026

Quick Overview

This question evaluates experimental design, statistical inference, causal estimands, subgroup analysis, data quality checks, and stakeholder-facing communication in the Analytics & Experimentation domain, targeting an applied, intermediate-to-senior data scientist.

  • medium
  • PayPal
  • Analytics & Experimentation
  • Data Scientist

Analyze an A/B test and present recommendation

Company: PayPal

Role: Data Scientist

Category: Analytics & Experimentation

Difficulty: medium

Interview Round: Onsite

You are given an offline take-home style project before an onsite interview. You must analyze an A/B test and present your findings in slides. Assume you receive a user-level dataset `experiment_events` with: - `user_id` (string) - `variant` (string; 'control' or 'treatment') - `assignment_ts` (timestamp, UTC) - `country` (string) - `platform` (string; 'ios', 'android', 'web') - `exposed` (boolean; whether the user actually saw the new experience) - `orders_7d` (int; orders within 7 days after assignment) - `revenue_7d` (float; revenue within 7 days after assignment) - `support_tickets_7d` (int) - `is_new_user` (boolean) You also have pre-period covariates in `user_pre_period`: - `user_id` - `orders_28d_pre` (int) - `revenue_28d_pre` (float) Tasks: 1) Define the primary metric and guardrails you would use to decide whether to ship. 2) Perform the core statistical analysis you would do (tests/CI) and list the sanity checks (e.g., SRM, balance). 3) Explain how you would handle noncompliance (`exposed = false` for some assigned users) and which estimand you’d report (ITT vs TOT). 4) Describe how you would check heterogeneous treatment effects (by platform, country, new vs existing users) without p-hacking. 5) Outline what your slide deck would contain and how you would communicate uncertainty and next steps to PM/Eng.

Quick Answer: This question evaluates experimental design, statistical inference, causal estimands, subgroup analysis, data quality checks, and stakeholder-facing communication in the Analytics & Experimentation domain, targeting an applied, intermediate-to-senior data scientist.

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PayPal
Dec 10, 2025, 12:00 AM
Data Scientist
Onsite
Analytics & Experimentation
1
0

You are given an offline take-home style project before an onsite interview. You must analyze an A/B test and present your findings in slides.

Assume you receive a user-level dataset experiment_events with:

  • user_id (string)
  • variant (string; 'control' or 'treatment')
  • assignment_ts (timestamp, UTC)
  • country (string)
  • platform (string; 'ios', 'android', 'web')
  • exposed (boolean; whether the user actually saw the new experience)
  • orders_7d (int; orders within 7 days after assignment)
  • revenue_7d (float; revenue within 7 days after assignment)
  • support_tickets_7d (int)
  • is_new_user (boolean)

You also have pre-period covariates in user_pre_period:

  • user_id
  • orders_28d_pre (int)
  • revenue_28d_pre (float)

Tasks:

  1. Define the primary metric and guardrails you would use to decide whether to ship.
  2. Perform the core statistical analysis you would do (tests/CI) and list the sanity checks (e.g., SRM, balance).
  3. Explain how you would handle noncompliance ( exposed = false for some assigned users) and which estimand you’d report (ITT vs TOT).
  4. Describe how you would check heterogeneous treatment effects (by platform, country, new vs existing users) without p-hacking.
  5. Outline what your slide deck would contain and how you would communicate uncertainty and next steps to PM/Eng.

Solution

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