Start by naming the entrance. “Installed in the week beginning 4 August” is an entrance. “Completed first value in that week” is a better one, because it throws out the people who only saw the mascot. The Glasgow team in our case notes learned that the expensive way. You can learn it here for the price of an evening.
Pick two ages, not twelve
Day 1, day 7, day 35. That is enough for most subscription products we see. Daily columns through day 30 flatter people who enjoy colour scales. They rarely change a roadmap. If something interesting happens on day 12, you will still see it in the day-7 to day-35 comparison, and then you may zoom. Zooming first is how afternoons vanish.
Compare a change, not a mood
A useful cohort pair is “before we moved first value” and “after.” A less useful pair is “this month versus last month,” which also contains season, ads, and a store feature you did not control. In class we force the pair to include a dated product change. If you cannot name the change, you are watching weather.
Write the sentence before you show the chart: “Learners who spoke a reply in sitting one returned at day 35 more often than learners who only opened the mascot.” If the chart cannot carry that sentence, the chart is decoration. Put decoration in an appendix. The Friday page gets the sentence.
People who hate spreadsheets are often the people who still have to present. This method is for them. The heatmap can stay in the analyst’s notebook, where it belongs, next to the caveats the funnel essay asked you to write.