Calculate variance for click-through rates
Last updated: March 5, 2026
Quick Overview
Given the following scenario about user conversion, calculate the the p-value.
CrowdStrike
March 5, 20260
5
653 solved
Given the following scenario about user conversion, calculate the the p-value.
CrowdStrike asks this during the Onsite 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
- 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
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
- 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?
- How would you handle interference between treatment and control?
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Browse Analytics QuestionsSample Answer
Problem Setup
The analytical question here is to determine whether there is a statistically significant difference in click-through rates (CTR) between two groups: a control group and a treatment group after implem...
Methodology
To calculate the p-value for the difference in CTRs between the control and treatment groups, we can use a two-proportion z-test. Here’s how:
- Define the null hypothesis (H0): There is no difference...
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