Nice article with a nice example:
Let’s look at an example:
Suppose you and I are to walk to a building. We agree that it will take one walking point to get there. That doesn’t mean one minute, one mile or even one kilometer. We just call it one walking point. We could have called it 2, 5, 10 or a million, but let’s call it 1.
What’s nice about calling this one walking point is that you and I can agree on that estimate, even though you are going to walk there while I hobble over there on crutches. Clearly you can get there much faster than I can; yet using walking points, we can agree to call it one point.
Next, we point to another building and agree that walking to it will take two points. That is, we both think it will take us twice as long to get to.
Let’s add a third building. This building is physically the same distance as the two-point building. So we are tempted to call it a two. However, separating us from that building is a narrow walkway across a deep chasm filled with boiling lava. The walkway is just wide enough that we can traverse it if we’re extremely careful. But, one misstep, and we fall into the lava.
Even though this third building is the same physical distance as the building we previously estimated as two walking points, I want to put a higher estimate on this building because of the extra complexity in walking to it.
As long as I’m cautious, there’s no real risk of falling into the lava, but I assure you I am going to walk more slowly and deliberately across that walkway. So slow, in fact, that I’m going to estimate that building as four walking points away.
Make sense? The extra complexity has influenced my estimate.