In the book, Alex takes his son and his boyscout troop out for an overnight hike. I won’t get into the fact that Alex forgot about the trip until the day of and had to be woken up by his son. Oh, and his son also packed everything – including Alex’s clothes. Maybe your factory wouldn’t be such a mess if you could remember shit, Alex.
The boyscout hike is an amazing part of the book because it’s 1. The first and only business book with a boyscout troop hike in it, and 2. It illustrates dependent events and statistical fluctuations perfectly.
In short, Alex realizes that a bunch of boys hiking in single file is sort of like moving a part through his plant. And, through this analogy, he starts to understand why throughput is affected by dependent events and variation.
Here’s how it works.
Imagine the troop walking on a trail in single-file. Nobody can pass the boy in front of him, and since the whole idea is to move as a single unit, progress is only made when everyone in the troop gets to a certain point on the trail.
What Alex witnesses is that he can’t keep the god damn line together. Faster boys toward the front of the line inevitably separate from slower boys in the middle. When someone stops to tie his shoe, everyone behind him gets held up. Individual boys sometimes run to try to catch up to the boy in front of them, but that costs more energy and can only do so much to shorten the line. Sometimes running just causes another gap to open up. The whole thing is a fucking mess and the troop has to get to the ridge by 5pm to make camp before dark!!
The breakthrough Alex eventually has is that the slowest kid needs to control the pace. No matter how fast everyone else goes, the whole troop isn’t going to get there until the slowest kid arrives.
He realizes that the best idea is to put the slow kid at the front of the line, and then organize everyone from slow to fast, such that the fastest kid is at the back of the line.
What this configuration accomplishes is a thing of beauty. Variations still happen – kids get distracted, stop to drink some water, adjust their packs – and the line spreads out…but the fast kids can recover easily and catch up. The line almost always stays nice and short (you’ll learn that this is equivalent to having a small inventory).
I’ll leave it here for now and we’ll come back to this in the next post. Should solidify the understanding.