VELOCITY - DEE JACOB [75]
On the first turn, they moved two pennies across the finish line – Zelda, having rolled a two, was only able to move two pennies of her four-penny inventory. But on the second turn, Zelda rolled a six. And she had six to move, because – with Amy helping her dad – she had received four from Harry on the previous turn.
“Come on! Roll those sixes!” Amy squawked.
They joked back and forth with each other. Ones were booed; sixes were cheered – and there were groans when the high rolls were for naught because the pennies in queue were less than the number rolled.
“All right! A six!” called Amy on the first turn of Week Three.
“Boxcar!” said her dad.
“Ah, nuts. I only have two,” Amy said, moving her two cents over.
Tom kept a tally on the pad of paper. In the first week, they “finished” fifteen pennies. The second week, sixteen. But the third week, only twelve. And in the fourth week of the month, also only twelve pennies. The grand total for the month: fifty-five cents.
“Not exactly the seventy cents you were targeting for the month,” said Tom. “It’s not even the easier target of sixty-five.”
“If we played it again, couldn’t the average improve?” asked Amy.
“In the Marines, we played this multiple rounds,” said Tom, “and let me tell you, fifty-five for the balanced system model is pretty good. Most rounds, we ended in the forties. I think one time my team did hit sixty, but we never once made the target. And did you notice what happened with the inventory?”
“The work-in-process? The pennies in process? The number grew,” said Amy.
Indeed, at one point in the third week, Ben had eighteen pennies in front of him. And it was not uncommon toward the end of the game month for there to be a dozen or more pennies waiting in queue in front of one or more of them around the table.
“We started with twenty pennies on the table,” said Tom, “and we ended the month with more than double that number – forty-six.”
“True, but this is not really a Lean model with pull-through inventory,” said Amy.
“No, it’s not. On the other hand it is a balanced system, and you can see the tendency of a balanced line when you have variability in combination with dependency.”
“Dependency? What does that mean?” asked Zelda.
“One thing depends on another having happened,” said Amy. “For one event to occur, a prior event has to have occurred. In order for the kids to be allowed to watch TV, they first have to have finished their homework.”
“And then there is interdependency,” said, of all people, Harry, chiming in. “Two or more conditions dependent on each other.”
“Right, Dad!” said Amy.
“Where are we again?”
His daughter patted him on the shoulder, saying, “You know, Dad, parts of your mind are still sharp.”
“And other parts,” Harry muttered, “not so good …”
“That’s the way the disease is,” said Zelda.
“Let’s do one more round,” said Tom. “But this time we’re going to run an unbalanced system, rather than a balanced one. We will unbalance the line by adding a constraint.”
“This sounds weird,” said Michelle. “Why would you do that?”
“Just because it’s Saturday night and we want to be wild and crazy,” said Tom. “Now, the way we’re going to unbalance the process line is everyone will now have two dice, but your mom will only have one die. So she will be the constraint. She will have half the processing capacity of each of the rest of you.”
Amy stuck out her lower lip and pouted.
“That means the least she can process will be one penny, and at the most six pennies. But the rest of us, including me as penny vendor, can move anywhere from one to twelve pennies. What do you think is going to happen? Will we move more pennies or fewer pennies than before? Will we do better than sixty-five? Seventy?”
“Less,” said Zelda. “Because Amy will be holding everything up.”
“I think it’ll be about the same as the