A closed test
The checkout banner that looked like a win until the split drifted
A Johor e-commerce lead sent us logs from a two-week banner test. Conversion lifted on the surface. The assignment ratio had slipped two points by day four. Once we restored the intended split in the analysis, the lift sat inside noise, and the banner stayed off the live template.
That is the work: not a prettier chart, but a decision that survives a sceptical finance question.