Calculate conditional probability for A/B test results
Last updated: August 4, 2025
Quick Overview
Given the following scenario about revenue per session, calculate the the p-value.
Workday
August 4, 2025206
3
3,228 solved
Given the following scenario about revenue per session, calculate the the p-value.
Workday asks this during the Phone Screen to assess your experimentation skills. They want to see how you define success metrics, design controlled experiments, and interpret results with appropriate statistical rigor.
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
How to Approach This
- Define success metrics carefully. A good metric is measurable, actionable, and aligned with business goals.
- Run experiments long enough to account for novelty effects and weekly seasonality.
- Use funnel analysis to identify where users drop off for maximum optimization impact.
- Segment results by key dimensions (platform, country, user cohort) to catch hidden patterns.
- Consider network effects and interference between treatment and control groups.
Possible Follow-up Questions
- 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 if you discover a bug in the logging during the experiment?
- How would you handle seasonality in your experiment?
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Browse Analytics QuestionsSample Answer
Problem Setup
The analytical question is to determine whether the revenue per session differs significantly between two user groups (A and B) in an A/B test conducted by Workday. The data needed includes:
- Revenu...
Methodology
To calculate the p-value for the difference in revenue per session between groups A and B, I would use a two-sample t-test assuming normal distribution of revenue per session in both groups. The assum...
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