Finding the drop
Unit 2 of 8 · Lesson 3 of 4Index
You have the map. Now you need numbers, and the data team's queue is eleven days long. Dev exports last month's counts for every arrow you named.
A funnel is a multiplication
- 01
Look for the steepest step
Line up how many people reached each step. One step loses far more of its arrivals than the rest. Start there.
Look for the steepest step - 02
Always ask: percent of what?
A rate is only useful with its denominator. Count the same people over the same window, or the numbers will argue with each other.
Always ask: percent of what? - 03
Split before you average
An average can hide a broken platform, country or bank. Split the drop by segment before you decide what it means.
Split before you average - 04
Data shows where, not why
The funnel tells you where people quit. It cannot tell you what they were thinking. That is the next lesson's job.
Data shows where, not why
Change one step. Follow the effect.
Interactive teaching example · All numbers and tickets are fictional.
1,000 × 80% × 50% × 80% × 90% = 288.0 expected completions. Baseline: 288. Rounded counts are illustrative; all other rates stay fixed.
How Airbnb handled it
The funnel pointed at the step. Going to look found the cause. You need both.
Airbnb, 2009
Airbnb's early listings in New York were not booking, and the numbers alone did not say why.
The founders flew out and found the photos were dark phone snapshots. They rented a camera and reshot listings themselves, and bookings in those listings went up.
Public commentary. No affiliation.
Doing it with AI, and where it breaks
Give a model your step counts and ask for the formula for each step rate and for the end to end impact of improving each step by 10 points.
Models are unreliable at multi step arithmetic and will state a wrong total confidently. Take the formulas, do the maths in a sheet.
Here are counts for each step of a funnel. Write the spreadsheet formulas for (1) each step's conversion rate and (2) the final conversion if any single step improved by 10 percentage points. Do not compute the numbers yourself.
Build it
A funnel sheet with step rates, a segment split, and a ranked fix list.
Google Sheets
The worked solution
Stuck, or want to compare?
There is a worked solution. Try the build first. Reading it before you have attempted anything is the fastest way to learn nothing.
Checkpoint
If you did the build, these take two minutes. If you cannot answer one of them, that is the part to go back to.
Moving on marks this lesson complete. Finish the build first, it is the part that counts.