Interpret a statistically significant lift of 2% from an experiment
Last updated: July 31, 2025
Quick Overview
An experiment shows a 3% lift with p=0.08. What conclusions can you draw? What are the caveats?
Dropbox
July 31, 202519
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3,874 solved
An experiment shows a 3% lift with p=0.08. What conclusions can you draw? What are the caveats?
Dropbox 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
- 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 you discover a bug in the logging during the experiment?
- 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
The analytical question here is to interpret the 3% lift observed in the experiment with a p-value of 0.08. To thoroughly analyze this result, we need data that includes the baseline conversion rate, ...
Methodology
Given the observed lift of 3% with a p-value of 0.08, we can imply that the result is not statistically significant at the conventional 0.05 level but is close. To analyze this, we can perform a hypot...
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