Central Limit Theorem -- Dickeson

How accurate do you want to be? Pick a number from the statistical table. If we want to manage the variance, we must continuously narrow that range of variance.

What causes the wide variance in "net" speeds of that press? The difference between gross and net press speed is caused by unplanned stops. Just as your net highway speed for a trip is regulated by the "rest" stops you have to make, net press speed is regulated by press stops. Cut stops to increase net speed and reduce the range of predictability variance. Reduce stops and decrease quality variance.