The initial median AND the annotations of the tests for particular alterations (PDSA cycles) You can compare observations made before and after your PDSA cycle using the median and annotations denoting particular changes.
Changes may not result in improvement or even be practical in practice without adequate testing. Changes can ultimately be made easier to execute and more sustainable by employing Plan-Do-Act-Study (PDSA) cycles in testing.
Testing fosters a stronger belief that a change will lead to advancement
PDSA cycles have a track record of gradually growing success for improved and modified ideas
Testing gives you more time to adjust to local conditions
Determine whether the adjustment needs to be adjusted to handle those adverse effects using PDSA cycles and testing