Guesstimate Explained

Guesstimate is an informal English portmanteau of guess and estimate, first used by American statisticians in 1934^[1] or 1935.^[2] It is defined as an estimate made without using adequate or complete information,^{[3] [4]} or, more strongly, as an estimate arrived at by guesswork or conjecture.^{[5] [6]} Like the words estimate and guess, guesstimate may be used as a verb or a noun (with the same change in pronunciation as estimate). A guesstimate may be a first rough approximation pending a more accurate estimate, or it may be an educated guess at something for which no better information will become available.

The word may be used in a pejorative sense if information for a better estimate is available but ignored.^{[7] [8]}

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;^[9]
• in cosmology, where the Drake equation is a well-known guesstimation method;^[10]
• in economics, where economic forecasts and statistics are often based on guesstimates; ^[11] and
• in software engineering, where new development of features and release timelines are based on effort guesstimates of tasks.

Lawrence Weinstein and John Adam's 2009 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 estimating the total number of miles that Americans drive in a year (about 2 trillion)^[12] and the amount of high-level nuclear waste that a 1 GW nuclear power plant produces in a year (about 60 tons).^[13]

See also

• Ansatz
• Back-of-the-envelope calculation
• Heuristic
• Scientific wild-ass guess

Sources

• Book: Weinstein , Lawrence . Adam, John A. . Guesstimation: Solving the World's Problems on the Back of a Cocktail Napkin . Princeton University Press . 2008 . 978-0-691-12949-5 .

External links

• The Fermi Project: Collection of guesstimates for practice

Notes and References

1. http://www.etymonline.com/index.php?term=guess guess
2. http://dictionary.reference.com/browse/guesstimate guesstimate
3. http://www.merriam-webster.com/dictionary/guesstimate guesstimate
4. http://encarta.msn.com/dictionary_1861615713/guesstimate.html guesstimate
5. http://www.bartleby.com/61/17/G0301700.html guesstimate
6. Compact Oxford English Dictionary guesstimate
7. "Guesstimate with confidence using confidence intervals" from back cover of Statistics for Dummies
8. http://www.thirteen.org/edonline/nttidb/lessons/sf/guesssf.html Guesstimate; Grades 4-6
9. http://www.timeshighereducation.co.uk/story.asp?storyCode=402275&sectioncode=26 Guesstimation: Solving the World's Problems on the Back of a Cocktail Napkin
10. http://wearentalone.googlepages.com/drake.html The Drake Equation
11. http://www.bizjournals.com/sanantonio/stories/2003/10/13/editorial3.html Economic outlooks often rely on guesstimation
12. Weinstein & Adam (2008) Problem 5.1
13. Weinstein & Adam (2008) Problem 10.5