Calculate conditional probability for coin flips
Last updated: July 25, 2025
Quick Overview
Given the following scenario about user conversion, calculate the the p-value.
ServiceNow
July 25, 202585
6
1,397 solved
Given the following scenario about user conversion, calculate the the p-value.
ServiceNow 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 would you do if a stakeholder wants to end the experiment early because initial results look good?
- How would you handle an experiment where the control and treatment groups are different sizes?
- How would you handle seasonality in your experiment?
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Browse Analytics QuestionsSample Answer
Problem Setup
To assess the user conversion rates when exposed to a new feature in ServiceNow, we need to determine the conditional probability of a user converting after being exposed to the feature. The analytica...
Methodology
For this analysis, we will use the Chi-Squared Test for Independence to compare the conversion rates between the treatment and control groups. This will allow us to determine if there is a statist...
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