Capture the baseline before you flip the flag
Feature flags promise reversible change. Impact analytics only works if you know what “before” looked like. Teams often enable a flag mid-week, then ask analytics for a verdict on Friday—with no agreed baseline window and a holiday spike in the middle.
Start with the decision you need: ship wider, hold, or roll back. That decision names the primary metric and two guardrails. Then pick an observation window long enough to cover weekday patterns in your Thai user base, and exclude known campaigns.
Write the plan down before traffic splits. When the readout arrives, the room argues about interpretation—not about whether the numbers were ever fair.