Why two windows?
Comparing early and recent averages reduces the influence of a single personal best.
Is it progress—or ordinary variation?
Paste repeated measurements from the same test. The lab compares two windows while keeping uncertainty visible.
YOUR MINI STUDY
Test a sequence.
Use 6–20 values collected with the same equipment, surface, warm-up, and timing method.
EXAMPLES
Vertical jump: higher is better. Sprint time: lower is better.
Better performance is
Enter at least six values, choose a direction, and analyze.
Why standard deviation?
It gives the change context: the same improvement means more when normal variation is small.
Why an interval?
A range communicates uncertainty more honestly than one decisive-looking estimate.