In this posting we will
continue building our Conflict Resolution Diagram by discussing how to surface
the Prerequisites for each requirement and then begin surfacing the assumptions
and injections for each entity. As we
said in our last posting, we intend to present this material in a slow,
methodical manner so the readers who aren’t familiar with the TOC Thinking
Processes can better understand how these techniques work.
Surfacing the PrerequisitesThe prerequisites are the necessary conditions that support the requirements. This is also the step that will surface the most likely conflict between achieving the requirements in the CRD. The prerequisites are commonly referred to as entities D and E.
If we look at the
requirement (entity B) in the CRD we are looking for the prerequisite
(necessary condition) that must exist just prior to “Production scheduled to
utilize available capacity.” What must
exist just prior to this requirement to make it possible? You can also read from entity B to try and
establish the prerequisite. In other
words, “In order to have production scheduled to utilize available capacity… I
must have what?” When you think about
utilizing the available capacity most people immediately think about “keeping
everyone busy - all the time!” On the
surface, that seems like the best and most effective way to utilize the
capacity. The best way to achieve that
would be to schedule production based on a “push” system. The constant release of products into the
system would maximize the probability of keeping everyone busy and utilizing
the maximum capacity! Let’s plug it in
and see what happens.
“In order to have
Production scheduled to utilize available capacity, I must have Production
scheduled based on the push system.”
Seems to make sense and it seems to fit.
The second
prerequisite is surface in the same manner.
It will be a necessary condition to support the second requirement
(Entity C). Again, ask the question:
“What must exist just prior to, “Production generates the maximum number of
products.” This can also be read, “In
order to have Production generate the maximum number of products, I must have
what? If we think about this
prerequisite it immediately implies a system of smooth flow, low
work-in-process (WIP) and short production lead-times, to get product through
the system fast. This thinking would
imply a “pull” system. In other words, release only when necessary instead of
releasing all the time.
With the second
prerequisite now added to the CRD the conflict now becomes obvious. In order to meet one requirement (entity B) I
must use the “push” system. In order to
meet the second requirement (entity C) is must use the “pull’ system. Both systems cannot exist at the same
time! It is not possible to “push” and
“pull” with the same schedule. With the
conflict now surfaced, the second part of the CRD analysis is focused on
breaking the conflict and determining the best solution to implement.
NOTE: When
building a CRD it is a common mistake for people to actually verbalize the
conflict in the requirements (B & C).
When you determine the requirements make sure they are requirements that
are needed to support achieving the objective.
If the requirements actually read more like two opposing thoughts then,
slide them out to D & E and look for new requirements to fill in B & C.
Surfacing the Assumptions and Injections
With the conflict
surfaced we now extend the CRD to look for a solution to the conflict. The way to accomplish this is to surface, and
evaluates, the assumptions that go with each arrow between the entities, either
your assumptions or someone else’s. The assumptions are the reason “why” the
stated necessary condition is important. In the CRD, each arrow between the
entities is a solid black line because they are supported by assumptions.
Assumptions can basically be in two categories – valid and invalid. Some assumptions, even though they are highly
preached and believed, can be invalid!
Challenging these assumption(s) is a way for logic to provide a pathway
to override the emotions of belief that support some invalid assumptions.
There are five (5)
arrows in the CRD on which assumptions can be surfaced. The next step is to surface the assumptions
on the arrows between the entity statements.
The purpose is to verbalize what those assumptions are and see if any
(minimum one) can be invalidated with an injection (new Idea) that overcomes
the assumption. An injection, once
found, should be powerful enough to overcome the existing assumption and
invalidate it. Once this happens the
conflict can be broken and the “new” injection (idea) can replace the old
assumption and dissolve the conflict.
We surface the
assumptions by asking the question -”Because?”
In order to have “A”, I much have “B”… because? The answers to the “because” question becomes
the “assumptions” that appears to make the statement valid. When surfacing
assumptions be BOLD. Don’t reject an
assumption because you don’t believe it.
The truth is, someone else might believe.
Let’s start by
surfacing assumption on the A à B arrow.
“In order to have
Production scheduled at the most effective level, I must have Production
scheduled to utilize available capacity, because…?”
1, Capacity really is limited. There is only so much you can do with what you have.
2. Production is measured on system efficiency. I there any other way to measure a system besides efficiency?
3.Operators need to be busy all the time. If they aren’t busy ALL the time we should send them home, or lay them off!
4. Operators are measured based on machine utilization. There has to be a way to measure the individual contributions to the system. Individual efficiency is a way to do that.
Transfer these
assumptions to the CRD.
Possible injections:
1. Capacity is scheduled
correctly. If capacity is limited, which it is, then,
scheduling it correctly will provide benefit.
2. Production is
measured on system throughput. Measuring system throughput will eliminate
the need to measure efficiency.
3. Operators are busy
only when they need to be busy. Synchronizing the production schedule based
on Drum-Buffer-Rope (DBR) will eliminate the need to be busy all the time and
be busy only when they need to be busy.
4. Operators are
measured based on system throughput. A radical change in measures from efficiency
to throughput. Measure the system and
not each individual operator.
Once the assumptions
and injections for A à B line have been
surfaced, we can move to the B à D line. The same thinking process will be employed
for ALL of the arrows. In our next
posting we will continue to develop the CRD.
Once again I want to
thank my good friend Bruce Nelson for writing this valuable series of post. In closing I want to let my reader base know
that a group of “TOC Experts,” who shall remain nameless, have deemed Bruce and
my methods as being incorrect and not in line with how Dr. Goldratt intended
the Thinking Processes to be used. I can
only tell you that our method has worked quite well for us over the years and
that we will continue using it. It’s
your choice as to whether you follow our method or some other method. Our purpose in this blog posting is simply to
demonstrate the power of the TP’s. In a
previous blog posting I wrote about the difference between being and optimizer
and a satisficer……we choose to be satisficers.
Bob Sproull
2 comments:
Bob
Respectfully - There's a huge difference between the comments made to you and your interpretation as your methods being incorrect. What I requested was that you make it clear when publishing work under the banner of TOC and the Thinking Processes that you at least acknowledge your source and not confuse people by not stating that you use Bill Dettmer's Logical Thinking Process methodology and not those used by Goldratt et al.
Jim, you made it very clear in your previous comments to me via email primarily that you didn't agree with what I had posted. As far as acknowledging Dr. Goldratt, I have told my readers on numerous postings how I feel about the late, great Dr. Goldratt and have given him credit for inventing the concepts and tools of TOC. It has always been my belief that when you learn how to use new tools that you should then make them your own and if there's a way to improve upon them, then you should do so. It is very clear to me that you are not a fan of my blog, and I respect that. So in conclusion, to all of my readers, I have never given credit only to Bill Dettmer for developing the Logical Thinking Processes, but what I have given him credit for is improving them...especially with the reintroduction of the IO Map, now known as the Goal Tree.
Bob Sproull
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