Calculate conditional probability for A/B test results

Last updated: September 14, 2025

Quick Overview

Given the following scenario about revenue per session, calculate the the p-value.

xAI
Analytics & Experimentation
Data Scientist
xAI
September 14, 2025
Data Scientist
Phone Screen
Analytics & Experimentation
Easy

17

5

3,056 solved


Given the following scenario about revenue per session, calculate the the p-value.

Analytics questions at xAI evaluate your ability to define metrics, design experiments, and derive actionable insights from data. This Phone Screen question tests your end-to-end analytical thinking.

What the Interviewer Expects
  • Define clear success metrics aligned with business goals
  • Propose a basic experimental design with control and treatment groups
  • Interpret results correctly and draw reasonable conclusions
  • Identify obvious confounding variables
Key Topics to Cover
A/B testing methodology
Network effects and interference
Sample size and power calculation
Guardrail metrics
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
  • What if you discover a bug in the logging during the experiment?
  • How would you handle seasonality in your experiment?
  • How would you handle interference between treatment and control?
  • What if the experiment shows a positive short-term effect but you suspect a negative long-term impact?
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