Guesstimate is a portmanteau of the words "guess" and "estimate", first used by American statisticians in 1934 [ [ "guess"] Online Etymological Dictionary] or 1935. [ "guesstimate"] Unabridged (v 1.1)] It is defined as an estimate made without adequate or complete information, [ [ "guesstimate"] Merriam-Webster On-line Dictionary] [ [ "guesstimate"] MSN Encarta Dictionary] or, more strongly, as an estimate arrived at by guesswork or conjecture. [ "guesstimate"] American Heritage Dictionary] [Compact Oxford English Dictionary [ guesstimate] ] Like the word estimate, guesstimate may be used as a verb or a noun (with the same change in pronunciation).

The word is sometimes classified as informal English. It may be used in a pejorative sense or as an informal synonym for "estimate". ["Guesstimate with confidence using confidence intervals" from back cover of Statistics for Dummies] [ [ Guesstimate; Grades 4-6] NTTI Lesson Plan]

Guesstimation techniques are used:
*in physics, where the use of guesstimation techniques to solve Fermi problems is taught as a useful skill to science students. [ [ Guesstimation: Solving the World's Problems on the Back of a Cocktail Napkin] , Tony Mann, Times Higher Education Supplement]
*in cosmology, where the Drake equation is a well-known guesstimation method. [ [ The Drake Equation]]
*in economics, where some economic forecasts and statistics are based on guesstimates. [ [ Economic outlooks often rely on guesstimation] , M. Ray Perryman, San Antonio Business Journal]

Lawrence Weinstein and John Adam's book "Guesstimation: Solving the World's Problems on the Back of a Cocktail Napkin", based on the course "Physics on the Back of an Envelope" at Old Dominion University, promotes guesstimation techniques as a useful life skill. It includes many worked examples of guesstimation, including the following problems:

*How many golf balls would it take to circle the Earth at the equator ?::Answer: about one billion (109). [Weinstein & Adam (2008) Problem 3.2]
*How many total miles do all Americans drive in a year ?::Answer: about two trillion (2x1012). [Weinstein & Adam (2008) Problem 5.1]
*How much high-level nuclear waste does a 1 GW nuclear power planet produce in a year ?::Answer: about sixty tons. [Weinstein & Adam (2008) Problem 10.5]

ee also

*Ballpark estimate


* cite book
last = Weinstein
first = Lawrence
coauthors = Adam, John A.
title = Guesstimation: Solving the World's Problems on the Back of a Cocktail Napkin
publisher = Princeton University Press
date = 2008
isbn = 9780691129495

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  • guesstimate — guess‧ti‧mate [ˈgestmt] noun [countable] informal an attempt to judge an amount or quantity by guessing it: • In these uncertain economic times, Wall Street earnings estimates more closely resemble guesstimates. guesstimate [ meɪt] verb… …   Financial and business terms

  • guesstimate — ☆ guesstimate [ges′tə mit; ] for v. [, ges′təmāt΄ ] Slang n. [ GUESS + (ES)TIMATE] an estimate based on a guess or conjecture vt. guesstimated, guesstimating to form a guesstimate of: Also sp. guestimate …   English World dictionary

  • guesstimate — guess ti*mate n. [from guess and estimate] an estimate based on little information, being little better than a guess. [PJC] …   The Collaborative International Dictionary of English

  • guesstimate — (v.) 1902, a blending of GUESS (Cf. guess) (v.) and ESTIMATE (Cf. estimate). Related: Guesstimated; guesstimating. As a noun, from 1906 …   Etymology dictionary

  • guesstimate — (also guestimate) informal ► NOUN ▪ an estimate based on a mixture of guesswork and calculation. ► VERB ▪ estimate in such a way …   English terms dictionary

  • guesstimate — UK [ˈɡestɪmət] / US noun [countable] Word forms guesstimate : singular guesstimate plural guesstimates informal a calculation of the size, value, or amount of something when all the facts are not available to you Derived word: guesstimate UK… …   English dictionary

  • guesstimate — 1. noun An estimate that is hardly any better than a guess, often because it is based on insufficient or unreliable data. 2. verb a) To make a guesstimate. b) To make a guesstimate …   Wiktionary

  • guesstimate — guess|ti|mate [ˈgestımıt] n informal [Date: 1900 2000; Origin: guess + estimate] an attempt to judge a quantity by guessing it →↑estimate ▪ Could you give us a guesstimate of the numbers involved? >guesstimate [ tımeıt] v [I and T] …   Dictionary of contemporary English

  • guesstimate — noun Etymology: blend of guess and estimate Date: 1923 an estimate usually made without adequate information • guesstimate transitive verb …   New Collegiate Dictionary

  • guesstimate — somewhere between guess and estimate guesstimate how many peas are in this jar …   Dictionary of american slang