all the excess space between all the boys. I have to make up for the accumula- tion of all their slowness.
Then I start to wonder what this could mean to me on the job. In the plant, we've definitely got both dependent events and statistical fluctuations. And here on the trail we've got both of them. What if I were to say that this troop of boys is analogous to a manufacturing system... sort of a model. In fact, the troop does produce a product; we produce 'walk trail.' Ron begins production by consuming the unwalked trail before him, which is the equivalent of raw materials. So Ron processes the trail first by walking over it, then Davey has to process it next, followed by the boy behind him, and so on back to Herbie and the others and on to me.
Each of us is like an operation which has to be performed to produce a product in the plant; each of us is one of a set of dependent events. Does it matter what order we're in? Well, somebody has to be first and somebody else has to be last. So we have dependent events no matter if we switch the order of the boys.
I'm the last operation. Only after I have walked the trail is the product 'sold,' so to speak. And that would have to be our throughput-not the rate at which Ron walks the trail, but the rate at which I do.
What about the amount of trail between Ron and me? It has to be inventory. Ron is consuming raw materials, so the trail the rest of us are walking is inventory until it passes behind me.
107
And what is operational expense? It's whatever lets us turn inventory into throughput, which in our case would be the en- ergy the boys need to walk. I can't really quantify that for the model, except that I know when I'm getting tired.
If the distance between Ron and me is expanding, it can only mean that inventory is increasing. Throughput is my rate of walking. Which is influenced by the fluctuating rates of the oth- ers. Hmmm. So as the slower than average fluctuations accumu- late, they work their way back to me. Which means I have to slow down. Which means that, relative to the growth of inventory, throughput for the entire system goes down.
And operational expense? I'm not sure. For UniCo, when- ever inventory goes up, carrying costs on the inventory go up as well. Carrying costs are a part of operational expense, so that measurement also must be going up. In terms of the hike, opera- tional expense is increasing any time we hurry to catch up, be- cause we expend more energy than we otherwise would.
Inventory is going up. Throughput is going down. And op- erational expense is probably increasing.
Is that what's happening in my plant?
Yes, I think it is.
Just then, I look up and see that I'm nearly running into the kid in front of me.
Ah ha! Okay! Here's proof I must have overlooked some- thing in the analogy. The line in front of me is contracting rather than expanding. Everything must be averaging out after all. I'm going to lean to the side and see Ron walking his average two- mile-an-hour pace.
But Ron is not walking the average pace. He's standing still at the edge of the trail.
'How come we're stopping?'
He says, 'Time for lunch, Mr. Rogo.'
'But we're not supposed to be having lunch here,' says one of the kids. 'We're not supposed to eat until we're farther down the trail, when we reach the Rampage River.'
'According to the schedule the troopmaster gave us, we're supposed to eat lunch at 12:00 noon,' says Ron.
'And it is now 12:00 noon,' Herbie says, pointing to his watch. 'So we have to eat lunch.'
'But we're supposed to be at Rampage River by now and we're not.'
'Who cares?' says Ron. 'This is a great spot for lunch. Look around.'
Ron has a point. The trail is taking us through a park, and it so happens that we're passing through a picnic area. There are tables, a water pump, garbage cans, barbecue grills-all the ne- cessities. (This is my kind of wilderness I'll have you know.)
'Okay,' I say. 'Let's just take a vote to see who wants to eat now. Anyone who's hungry, raise your hand.'
Everyone raises his hand; it's unanimous. We stop for lunch.
I sit down at one of the tables and ponder a few thoughts as I eat a sandwich. What's bothering me now is that, first of all, there is no real way I could operate a manufacturing plant without having dependent events and statistical fluctuations. I can't get away from that combination. But there must be a way to over- come the effects. I mean, obviously, we'd all go out of business if inventory was always increasing, and throughput was always de- creasing.
What if I had a balanced plant, the kind that Jonah was saying managers are constantly trying to achieve, a plant with every resource exactly equal in capacity to demand from the mar- ket? In fact, couldn't that be the answer to the problem? If I could get capacity perfectly balanced with demand, wouldn't my excess inventory go away? Wouldn't my shortages of certain parts disappear? And, anyway, how could Jonah be right and every- body else be wrong? Managers have always trimmed capacity to cut costs and increase profits; that's the game.
I'm beginning to think maybe this hiking model has thrown
109
me off. I mean, sure, it shows me the effect of statistical fluctua- tions and dependent events in combination. But is it a balanced system? Let's say the demand on us is to walk two miles every hour-no more, no less. Could I adjust the capacity of each kid so he would be able to walk two miles per hour and no faster? If I could, I'd simply keep everyone moving constantly at the pace he should go-by yelling, whip-cracking, money, whatever-and ev- erything would be perfectly balanced.
The problem is how can I realistically trim the capacity of fifteen kids? Maybe I could tie each one's ankles with pieces of rope so that each would only take the same size step. But that's a little kinky. Or maybe I could clone myself fifteen times so I have a troop of Alex Rogos with exactly the same trail-walking capac- ity. But that isn't practical until we get some advancements in cloning technology. Or maybe I could set up some other kind of model, a more controllable one, to let me see beyond any doubt what goes on.
I'm puzzling over how to do this when I notice a kid sitting at one of the other tables, rolling a pair of dice. I guess he's practic- ing for his next trip to Vegas or something. I don't mind-al- though I'm sure he won't get any merit badges for shooting craps -but the dice give me an idea. I get up and go over to him.
'Say, mind if I borrow those for a while?' I ask.
The kid shrugs, then hands them over.
I go back to the table again and roll the dice a couple of times. Yes, indeed: statistical fluctuations. Every time I roll the dice, I get a random number that is predictable only within a certain range, specifically numbers one to six on each die. Now what I need next for the model is a set of dependent events.
After scavenging around for a minute or two, I find a box of match sticks (the strike-anywhere kind), and
