Product Manager Math, Part ∞
Weekly site visitors are down 12%, what should you do? Maybe nothing.
This type of question comes up very often in PM interviews.
One question to ask before you act: Was there a holiday in any country in which a meaningful portion of your visitors come from?
Did that holiday fall in the same week last year? Did it impact traffic in the previous year?
People who work in retail and e-commerce are aware of holidays in countries that their customers even that they might not.
Web traffic movers that have caused me brief but temporary panic in recent years have included Singles Day and Spring Festival.
Depending on your product, you may want to become an expert in these topics. Equally important for product managers is the skill of learning to ignore false signals until actionable trends emerge.
As a general rule, I find it hard to trust any single weekly number. The chance of a holiday causing traffic to fluctuate in weekly data is high. The number of holidays from week to week is highly variable. It varies much less from month to month.
My son and I worked out the math on this. I thought it would be a fun father-son project. He has taken up fencing instead.
In general, I find that it takes two weird weekly reports in a row to make the data worth asking questions about. It usually takes three abberant data points to make a trend worthy of investigation.
Any double-digit monthly move gets marked in yellow for further study.
Two important exceptions to be aware: Traffic and sales numbers that all down, and occur in month 7 (vacations) or 12 (14 spiritual holidays observed globally.) Experience product managers know you can depend on these patterns every year.
Twice a year, the PM math does itself.