Critical Chain - Eliyahu M. Goldratt [56]
Jim and Johnny are now both at the board writing some equations.
But what if I can beat her at her own game? Not a chance.
Why do I take for granted that it's beyond me to solve the projects' problems?
"Rick?" Charlene touches my arm. "I need to know this stuff. Do you mind letting Johnny continue?"
I stare blankly at her.
"In two hours I have a class to teach, and you are wasting our time now."
She is so self-centered. I need to know this stuff even more than she does.
"Why are you picking on me?" I say.
She doesn't answer. Instead she turns back to them. "So, the first step is ‘identify.' Johnny, Jim, can we proceed?"
"And the next steps," I say, "are ‘exploit,' then ‘subordinate,' then ‘elevate' and ‘go back.' That's simple. My question is, how do I convert it into a logistical solution? Something practical."
Jim returns to his seat. Johnny wipes their scribbles from the board and writes the remaining four steps.
When he finishes, he turns around, and half seriously, half sarcastically he asks me, "Can I use an analogy?"
"Why not?"
He turns back to the board and adds legs and noses to the circles. "Now they are a troop of soldiers on a march. Do you see the analogy to a plant?"
We don't.
"The first row of soldiers is walking on virgin road, processing raw material. Each row in turn processes the same piece of road until the last row releases the finished goods, the part of the road the troop, as a whole, has left behind."
"Now I see," says Charlene. "It's slightly confusing at first because in a plant the machines are fixed and material is moving, here it's the opposite. But I agree, it doesn't matter."
"If the first row consumes raw materials," Johnny continues, "and the last row releases finished goods, the distance between the first and last rows is work-in-process inventory. In this analogy we can see the inventory visually."
I'm not interested in inventory, it's not a factor in projects. "What about lead time?" I ask.
"It's the same," Johnny answers. "Production lead time is the time elapsed from the minute the first soldier stepped on a particular point until the last soldier stepped on the same point. So, the bigger the distance between the first row and the last row, the longer the lead time. Work-in-process inventory and lead time are twin brothers."
I don't have a problem with it, I just want him to talk in terms of lead time rather than inventory.
"When the troop leaves the camp," Johnny continues to explain, "the soldiers are packed together. But when we look at the same troop two miles down the road, what do we see? They are spread all over the countryside."
"Lead time has gone through the roof," I comment to myself.
"The officer will stop the troop, regroup the soldiers and then they'll continue. Stopping the troop means that throughput has been lost. We see that even in this simple ‘plant' there are problems. On average, lead time is too long, and from time to time throughput is lost."
I start to like Johnny's analogy.
He turns to Charlene. "What happens if we use efficiencies to judge the performance of each soldier?"
It's an interesting question. How does one go about answering it?
Charlene goes about it systematically. Slowly she says, "Being efficient means doing more in a given time period. In our analogy, it translates into ‘walk faster."'
Picking up speed she continues, "That's exactly what we want. We want the soldiers to move faster. I do not see any problem."
Neither do I.
"Do we want every soldier to move faster?" Johnny asks her, "or do we want the troop as a whole to move faster?"
"What's the difference?"
"You're forgetting that we have a bottleneck," and he points to the solider bearing the big X. "The rate at which the troop as a whole moves is dictated by the rate of the bottleneck. Our X fellow is not the first soldier. If we encourage each soldier