Explain p-value with an example

Last updated: November 7, 2025

Quick Overview

Explain p-value in simple terms and provide a concrete example.

DoorDash
Analytics & Experimentation
Data Scientist
DoorDash
November 7, 2025
Data Scientist
Take-home Project
Analytics & Experimentation
Easy

172

6

3,458 solved


Explain p-value in simple terms and provide a concrete example.

This analytics question from DoorDash's Take-home Project 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
  • 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
Network effects and interference
Novelty and primacy effects
Simpson's paradox and ecological fallacy
Segmentation and heterogeneous effects
Sample size and power calculation
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 seasonality in your 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?
  • What would you do if a stakeholder wants to end the experiment early because initial results look good?
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