LOOKING FOR A SOLUTION
So, we have two conflicts here. Both are caused by the
uncertainty with which we live. Can we eliminate the existence
of Murphy? This would be a nice solution. Without
any uncertain events disrupting the planning—the execution should
simply follow the plan and that's it.
TOC proposed a structured way to analyze such a
problem. As the entity in box D seems necessary to
achieve the one at B, and D' is necessary for C (and B
and C for the ultimate objective at A), we should reveal
all the basic assumptions behind the claim: we need D
in order to achieve.
Each of the basic assumptions provides an opportunity
to eliminate the conflict if we find a way to challenge the
assumption, meaning find a solution where
the assumption is not valid.
Consider, for instance, assumption #1. If we are in a market
that does not demand any
predictable performance from us, as are the
rest of the stakeholders, then
we have eliminated the
can replan every time Murphy acts. In a
way, a stand-up
comedy show has a market that requires unpredictability, so let the
performer surprise us. In the vast majority of the markets,
surprises are not welcome.
TOC chooses to challenge assumption #5: Murphy
forces substantial changes to the optimal plan/schedule.
How can we plan in such a way that Murphy won't
be able to disrupt the planning?
When we include an appropriate protection mechanism
within the planning!
Can we protect every detail that happens to be included in the
plan? That is certainly not practical.
But, if we concentrate the protection on the few critical
parts of the planning, we might then immunize our
planning against most of the common disruptions.
Certainly, the critical parts of any planning are the
planning objectives. The objectives of any production
schedule include shipping every firm order on time and of high
quality. The objective of any project planning is to finish on time,
within budget, and according to specifications.
The objective of any budgeting is to prevent
wasting money while allowing the necessary expenses
to be made.
So, we certainly need to protect the objectives of the
planning from disruptions. In order to do that, we may
need to define some critical intermediate objectives that must be
met. TOC claims only a few truly critical intermediate
objectives exist in reality. If we protect those
critical elements within the plan, we have a great chance
of meeting all the objectives.
But, one might raise a reservation. As Murphy can be
pretty active, how can we eliminate the chance that the
planned protection will be fully exhausted? Out of 1,000
small incidents that act against us every week, one or
two might be large enough to pierce the protection we've
installed. When we look for thousands of material items,
one item may be missing for such a length of time that
the complete planned protection disappears and real
damage starts to accumulate.
The TOC answer holds special insight. Let's call the
special protection mechanisms buffers. The idea is to
monitor the state of the buffers and identify the situation
where a buffer is almost exhausted. Then, special
actions should be taken to fix that. In other words, expediting
takes place only when one of the planned buffers
is consumed to the point that it threatens a critical
element of the planning.
Challenging assumption #5 eliminates the conflict. It
clearly states that we should replan only in very rare cases.
In the majority of the cases, the plan along with its imbedded
buffers is executed as is. In some cases expediting
efforts are taken to fix a truly serious situation.