Sanity Checks: Duplicated Rows, Impossible Rates and Totals That Don't Add Up
This lesson is part of the course
In this lesson
You audit a daily export before using it: flag duplicated dates, count impossible days, find rows whose reported conversion is wrong, and explain the gap to the dashboard total.
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Lessons in this course
- Warm-Up: Clarifying the Question, Points vs Percent and Share-of-Total Traps Locked
- SQL-Style Questions: Joins with XLOOKUP, Unmatched Rows and GROUP BY with SUMIFS Locked
- Metric Definitions: Active Users, Conversion and Why the Denominator Decides Locked
- Distribution Questions: Mean vs Median vs p90 and the Effect of One Outlier Locked
- Quick A/B Read: Conversion per Variant, Lift in Points and "Is It Worth Shipping?" Locked
- Cohort Retention: Months Since Signup, the Cohort Grid and Pooled vs Average Rates Locked
- Sanity Checks: Duplicated Rows, Impossible Rates and Totals That Don't Add Up Locked
- Capstone: A Timed Take-Home – Net Revenue, Refund Rate, Revenue by Channel and One Chart Locked