Intentional efforts made for the sake of receiving process feedback.
Because Feedback is Key to Learning, and we cannot study what we cannot measure, it is often necessary to manufacture feedback into your process/system.
Experiments are essentially excuses for creating feedback.
Surveys are a rudimentary form of feedback. They serve as a lagging proxy measure for actual effectiveness. (Proxy Measures, Lagging Measures)
I much prefer situations where you can insert frictionless feedback at multiple points in a process, giving a chance for Leading Measures from early in the process.