Metric design · Analysis note
When one metric produces two answers, inspect the denominator
A practical definition card for aligning population, eligibility, windows, deduplication, and exclusions.
Insight library
Working through analysis questions
Notes on funnel diagnosis, product instrumentation, experiment design, segmentation, retention, and repeat purchase.
Retention · Repeat purchase
Retention and repeat purchase need different cohorts
Defining populations, starting events, windows, and mature observation periods for activity retention and repeat purchase.
User segmentation · Analysis design
Useful segments are not the smallest segments
Choosing actionable, interpretable user groups with stable samples, starting from the analysis question.
Experiment design · Pre-launch review
A pre-launch checklist for an A/B test
Reviewing decisions, assignment, measures, duration, and stopping rules before a product experiment begins.
Product instrumentation · Data definitions
Six questions an event dictionary should answer
How to document event meaning, firing rules, fields, identity, versions, and ownership for reviewable instrumentation.
Funnel diagnosis · Work note
Four checks for a sudden funnel drop
A hypothetical dataset for separating traffic mix, product paths, instrumentation, and behavior changes.
Experiment design · Product decisions
When clicks rise and completions do not
A hypothetical product experiment about conflicting metrics, experiment goals, and the decision the test is meant to support.