Critical Chain - Eliyahu M. Goldratt [19]
Mark, Ruth and Fred are sitting in their tiny office, reading each other's reports. Mark is the first one to finish. He waits patiently for the others. He speaks only after Fred puts his papers on the table. "What do you think?"
"It seems," Ruth slowly says, "that what we have found supports what we've learned in class. People do give their ‘realistic estimates' according to their worst, past experience."
"That's what it looks like," Mark agrees. "Except for one over-confident individual. In all other cases, I would say that people tend to give estimates that cover their butts. Maybe Dr. Silver is right, maybe there is a lot of safety. And if so . . ."
"Wait," Fred interrupts him. "That is the impression we got by talking to the engineers."
"And even more so to the purchasing department," Mark must add. "Do you really believe that it takes seven weeks to get a lousy connector?"
"I agree. But I think that you are overlooking something." Fred runs his fingers through his thick black hair.
They wait for him to continue.
"In some of our cases, the work is already completed. And you know what? The original estimates were not far off. Out of the four I checked, in one case the work was reported complete ahead of time. In two it was on time, and in one it was way off. In any case, I didn't see this ‘two hundred percent plus' safety."
"Maybe time estimates are a self-fulfilling prophesy?" Ruth speculates.
"What do you mean?" Mark is puzzled.
"Remember what we learned in production?" Ruth asks.
"Ruth," Mark answers desperately, "since we got this lousy assignment we've learned so many things about so many subjects. Can you be a bit more specific?"
"We saw the same phenomenon in production."
Sighing, Mark begs, "Be much more specific."
"Remember that tall, material manager, the one with the beard?"
"Steve? The creep you had a crush on? Of course I remember. How can we forget?" Fred teases her.
"I didn't have a crush on him. Besides, he is married." She turns back to the subject. "Steve told us that his plant got too many complaints about late deliveries; they had lousy due-date performance. So they started to promise their clients three weeks delivery time instead of two. That gave him the ability to release the work a week earlier."
"And nothing changed," Mark recalls. "They continued to suffer from the same lousy due-date performance."
"They said the work would take two weeks, it took two weeks plus. They added more safety time, and said that it would take three weeks, it took three weeks plus. A self-fulfilling prophecy," Ruth summarizes.
"Yes, but that's because production is different," Fred argues. "In production, most of the time parts spend in the plant they are waiting in queues in front of machines, or waiting for another part in front of assembly. Most of the lead time is not actual production, it's in wait and queue. That's not the case in projects."
"And if Dr. Silver is right, and each step in a project contains so much safety? What then? Then in projects also most of the lead time is wait and queue."
"Ruth. Fred. Calm down. Let's think."
Another half an hour of stormy debate doesn't lead them to any conclusions.
"Can we conclude," Mark tries to put an end to it, "that it looks promising but we don't have enough to turn it into any practical line of action?"
"No," says Fred. "I don't think that our findings confirm that there is a lot of safety."
Before the debate starts again from scratch, Mark suggests a compromise, "Let's gather much more data."
Ruth doesn't agree. "What's the point," she says. "We don't have to assemble more data, it will not help us figure out why we have a self-fulfilling prophesy. We have to think."
"Fine," Mark smiles. "You'll think, we'll assemble more data."
"If in some mysterious way your data proves that there is not so much safety, I'll never forgive you," she warns them.
"Why is it so important to you to be right?" Fred asks. "Just because I teased you about Steve?"
"Forget Steve, I have a