Work out corrective action effectiveness instantly with clear inputs, formula shown and shareable results.
Effectiveness is the proportional reduction in defect rate after the corrective action. Verification requires enough post-action volume to distinguish the improvement from noise, and the residual rate matters as much as the reduction — an 80% cut that still leaves a significant defect stream is not a closed problem.
Effectiveness
Effectiveness % = (rate before - rate after) x 100 / rate before
Saving
Annual saving = (rate before - rate after) x annual volume x cost per defect
Enough that the expected number of defects at the old rate would be at least five to ten. Declaring success after a handful of good units is the commonest cause of recurrence.
That means the containment worked but the root cause was not eliminated, or the fix depended on attention that has since lapsed. Actions that rely on vigilance rather than design rarely hold.