The number 3 is a hidden number of importance for the engineer. That means that the engineer may or may not consciously think of it as an important number, but it is important, nonetheless. I say that mostly to be able to use the word, “nonetheless”.

Anyway, 3 is the minimum number of estimates an engineer will want to be “comfortable” with a decision on buying an item. The item may be a new car, a computer, or a sandwich. The word “comfortable” is in quotes because we need to remember that this is not an emotional “comfortable”, rather one of having a sense that things are right. In that way, it is a logical “comfortable”.

The way an engineer thinks of this concept of 3 is the following: Getting one quote is just plain wrong. The seller can raise the price and you would never know, thus ripping you off. Having two quotes, well, that is better, but if they are quite different from each other, it is difficult to know what the true value is. Having 3, and here I should say at least 3, the engineer has a great chance of seeing either all three estimates bunch up together, or two be close and the third be the outlier. Outliers are bad. Consider the word itself, a combination of “out” which is negative, and “lier” which sounds like “liar”, also negative.

Having 4 or 5 or 6 estimates is better, but running around getting all those quotes gets somewhat wasteful at some point, and making sure it is the same product with the same features gets more difficult the more comparisons one makes. So the engineer is “content” (a logical content) with getting 3 quotes. This is helpful if shopping with an engineer, particularly if you are a spouse who thinks just walking into one car dealership and buying the first car you like (especially if color is one major factor) is the way to go…