Business runs on estimates. “How long do you think that might take?” we naively ask. Then when someone tells us how long they think something might take, we write that down and hold them to it.

Merriam-Webster’s says the very word “estimate” means to roughly calculate or judge the value, number, quantity, or extent of something. “Roughly”... “judge.” We know that estimates are always wrong enough to be lottery-worthy when they are right.

Here are five estimate pathologies that cause us nothing but pain.

1. Guarantism: the belief an estimate is actually correct

When someone gives you a number, you believe it. Numbers are definite. They have credibility. When a plumber says, “This’ll probably cost ya about $600,” your head immediately sets a price at $600. This is where we explore ideas of accountability. We believe the estimate is correct, and we’ll hold that plumber accountable even though he clearly said “probably” and “about.” Dollars, dates, and milestones become truths the moment they are uttered.

 …