What’s the difference between estimate and guess?
One way to distinguish between them is degree of care taken when we arrive at a conclusion. A conclusion about how much effort work will take. How much it will cost to perform that work. If that work will hve any risk associated with it.
Estimate is derived from the Latin word aestimare. “To Value.” The term estimate is also the origin of estimable, meaning “capable of being estimated” or “worthy of esteem", and of esteem, which meaning “regard."
To make an estimate means to judge - using some method - the extent, nature, or value of something, with the implication that the result is based on expertise, data, a model, or familiarity. An estimate is the resulting calculation or judgment of the outcome or result. The related term is approximation, meaning “close or near.” Estimates have a measure of nearness to the actual value. We may not be able to know the actual value, but the estimate is close to that value. The confidence in the estimate adds more information about the nearness of the estimate to the actual value.
To guess is to believe or suppose, to form an opinion based on little or no evidence, or to be correct by chance or conjecture. A guess is a thought or idea arrived at by one of these methods. Guess is a synonym for conjecture and surmise, which like estimate, can be used as a verb or noun.
One step between a guess and an estimate is an educated guess, a more casual estimate. An idiomatic term for this conclusion is “ballpark figure.” The origin of this American English idiom, which alludes to a baseball stadium, is not certain. One conclusion is is related to “in the ballpark,” meaning “close” in the sense that one at such a location may not be in a precise location but is in the stadium.
We could have a hunch or an intuition about some outcome, some numerical value. Or we could engage in guesswork or speculation.
An interesting idea is “Dead reckoning” means the same thing as guesswork, though it originally referred to navigation based on reliable information. Near synonyms describing thoughts or ideas developed with more rigor include hypothesis and supposition, as well as theory and thesis.
A guess is a casual, spontaneous conclusion.
An estimate is based on some thought and/or data.
If those paying you can accept a Wild Ass Guess then you're probably done. If they have tolerance (risk tolerance) for loosing their value at risk if you're guess is wrong, then go ahead and Guess. Otherwise some form of estimate is likely needed to inform your decision about some outcome in the future that is uncertain.
