Laboratory / Mathematics
Probability as evidence
Draw repeated samples from a skewed population. Compare the changing sample values with the steadier distribution of sample means as sample size grows.
What changed
The sample contains 28 observations. Sample size changes uncertainty; skew changes the population being sampled.
Return to the route
Experiment after prediction.
Before changing a control, say which visible feature should move and which should remain invariant. That prediction is the useful part of the experiment; motion alone is not evidence.