Variability in the Production Process... at the core of a web of influences, leads immediately to difficulties in keeping to planned production schedules. When production runs go wrong, then in turn schedules over-run to produce the quantities required or, product quality isn't adequate... which leads to lateness or additional runs to make up for lost product (eg. rework). Those factors in turn ripple out to affect other functions, which in turn interact with other factors to generate a web of complex interactions which are very difficult to predict with certainty, or to manage.

The apparent complexity can make it very difficult to understand what is happening or to uncover root-causes. Fortunately, here are tools available by which to unravel the complexity and bring clarity to an otherwise confusing and intractable situation.