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If you are interested in this you might also like the book “The Goal”. It is a business novel introductions TOC (the Theory of Constraints) which IMHO is the #1

If you are interested in this you might also like the book “The Goal”. It is a business novel introductions TOC (the Theory of Constraints) which IMHO is the #1 most efficient way to run a company/team/process/…

kqr 4y ago
The problem with the theory of constraints is that it, from my understanding, uses inner constraints to determine boundary ingress rates. This causes higher variation than necessary. When a bottleneck is introduced, you will have a lot of crap backed up in front of it because you ran upstream processes at high rates into the bottleneck – even though you knew the bottleneck was there. When the bottleneck is lifted, you instead have upstream processes starved waiting for the flow from the boundary to come. A better alternative in the face of some variation is local signalling like kanban. This will run upstream processes at just the right rate all the way back to, and including, boundary ingresses.
- steppi 4y ago
  This problem actually comes up in The Goal. After the characters lift the bottlenecks in their factory, things go smoothly for a while but then they start to see starvation in other areas like you mentioned. The solution they come up with involves local signaling and also data collection and analysis to understand the timeframes in play within the factory. The following excerpt is from Chapter 26. Then I said, "Fine, but how do we time each release of material so it arrives at the bottleneck when it's needed?" Stacey said, "I'm not sure, but I see what you're worried about. We don't want the opposite problem of no work in front of the bottleneck." "Hell, we got at least a month before that happens, even if we released no more red tags from today on," said Bob. "But I know what you mean. If we idle the bottleneck, we lose throughput." "What we need," I said, "is some kind of signal to link the bottlenecks with the release-of-materials schedule." Then Ralph, to my surprise, spoke up and said "Excuse me, this is just a thought. But maybe we can predict when to release material by some kind of system based on the data we've kept on both the bottlenecks."
  - kqr 4y ago
    Yes, but also no. Prediction implies somewhat steady flow. That is of course the ideal! If you know roughly how much is going to be needed when you can just run things to schedule and you don't need any signals at all! The problematic case is when variation is too big for that. That's when (from my memory -- was a while since I read the books) Goldratt leans on global ingress control instead of local signaling. But I do realise I may be misremembering. I should probably re-read some time soon.
    - tome 4y ago
      I read it more recently than you and your memory matches mine. I was always surprised The Goal taught a push-based method rather than a pull-based one.
      - deterministic 4y ago
        What I learned from "The Goal" is that any business/system will always have a single bottleneck that dictates the max throughput of the whole business/system. So as a manager it is your #1 objective to find that bottleneck and remove it. And the moment you remove it, the max throughput of the whole business/system improves until some other bottleneck is now limiting throughput. So you repeat finding and fixing that bottleneck etc. There are of course different ways to fix the bottleneck. Kanban is a famous example of one. However even with Kanban the business will still have a bottleneck that limits throughput.
    - steppi 4y ago
      Got you. It seems like I'm the one misremembering. I thought they'd gotten more sophisticated than that by the end. I guess the story makes the ideas seem more powerful than they'd appear when laid out in a straight-forward way against competing processes.
deleted 4y ago
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kqr 4y ago

The problem with the theory of constraints is that it, from my understanding, uses inner constraints to determine boundary ingress rates. This causes higher variation than necessary. When a bottleneck is introduced, you will have a lot of crap backed up in front of it because you ran upstream processes at high rates into the bottleneck – even though you knew the bottleneck was there. When the bottleneck is lifted, you instead have upstream processes starved waiting for the flow from the boundary to come. A better alternative in the face of some variation is local signalling like kanban. This will run upstream processes at just the right rate all the way back to, and including, boundary ingresses.

steppi 4y ago
This problem actually comes up in The Goal. After the characters lift the bottlenecks in their factory, things go smoothly for a while but then they start to see starvation in other areas like you mentioned. The solution they come up with involves local signaling and also data collection and analysis to understand the timeframes in play within the factory. The following excerpt is from Chapter 26. Then I said, "Fine, but how do we time each release of material so it arrives at the bottleneck when it's needed?" Stacey said, "I'm not sure, but I see what you're worried about. We don't want the opposite problem of no work in front of the bottleneck." "Hell, we got at least a month before that happens, even if we released no more red tags from today on," said Bob. "But I know what you mean. If we idle the bottleneck, we lose throughput." "What we need," I said, "is some kind of signal to link the bottlenecks with the release-of-materials schedule." Then Ralph, to my surprise, spoke up and said "Excuse me, this is just a thought. But maybe we can predict when to release material by some kind of system based on the data we've kept on both the bottlenecks."
- kqr 4y ago
  Yes, but also no. Prediction implies somewhat steady flow. That is of course the ideal! If you know roughly how much is going to be needed when you can just run things to schedule and you don't need any signals at all! The problematic case is when variation is too big for that. That's when (from my memory -- was a while since I read the books) Goldratt leans on global ingress control instead of local signaling. But I do realise I may be misremembering. I should probably re-read some time soon.
  - tome 4y ago
    I read it more recently than you and your memory matches mine. I was always surprised The Goal taught a push-based method rather than a pull-based one.
    - deterministic 4y ago
      What I learned from "The Goal" is that any business/system will always have a single bottleneck that dictates the max throughput of the whole business/system. So as a manager it is your #1 objective to find that bottleneck and remove it. And the moment you remove it, the max throughput of the whole business/system improves until some other bottleneck is now limiting throughput. So you repeat finding and fixing that bottleneck etc. There are of course different ways to fix the bottleneck. Kanban is a famous example of one. However even with Kanban the business will still have a bottleneck that limits throughput.
  - steppi 4y ago
    Got you. It seems like I'm the one misremembering. I thought they'd gotten more sophisticated than that by the end. I guess the story makes the ideas seem more powerful than they'd appear when laid out in a straight-forward way against competing processes.

deleted 4y ago

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