Currently, sample rate for a recipe is expressed as a filter in the filter expression, and uses the percentage value (1 == 100%, 0.5 == 50%, etc). The UX for this isn't great though, and there are a few ideas on how to improve it: - Represent sample rate as "X out of Y users", e.g. "|stableSample(1, 10000)". - Add a small sample rate calculator next to the filter expression editor to turn a "1 out of 10000" number into a percentage value. This bug is for addressing the issue, but isn't tied to a particular solution.