Book 26, Question 102
Why do inventors use rulers and timers instead of eyeballing a test?
Guessing can be fooled by what you hope to see.
Measuring gives numbers that everyone can check. A timer, ruler, or scale shows how fast, long, or heavy something is. Measuring the same thing several times and finding the average makes results more trustworthy. Numbers also show whether version two is truly better than version one, and by how much.