Editing Fudge factor

{{short description|Ad hoc element introduced into a calculation}}
A '''fudge factor''' is an [[ad hoc]] quantity or element introduced into a [[calculation]], [[formula]] or [[Scientific modelling|model]] in order to make it fit observations or expectations.  Also known as a '''correction coefficient''', which is defined by
: <math> \kappa_\text{c} = \frac{\text{experimental value}}{\text{theoretical value}}</math>

Examples include Einstein's [[cosmological constant]], [[dark energy]], the initial proposals of [[dark matter]] and [[inflation (cosmology)|inflation]].<ref>{{citation |title=Einstein's Greatest Blunder?: The Cosmological Constant and Other Fudge Factors in the Physics of the Universe |author=Donald Goldsmith |publisher=Harvard University Press |year=1997 |isbn=9780674242425}}</ref>

== Examples in science ==
Some quantities in scientific theory are set arbitrarily according to measured results rather than by calculation (for example, the [[Planck constant]]). However, in the case of these [[fundamental constants]], their arbitrariness is usually explicit. To suggest that other calculations may include a "fudge factor" may suggest that the calculation has been somehow tampered with to make results give a misleadingly good match to experimental data.

=== Cosmological constant ===
In theoretical physics, when [[Albert Einstein]] originally tried to produce a [[general theory of relativity]], he found that the theory seemed to predict the gravitational collapse of the universe: it seemed that the universe should be collapsing, and to produce a model in which the universe was ''static and stable'' (which seemed to Einstein at the time to be the "proper" result), he introduced an expansionist variable (called the [[cosmological constant]]), whose sole purpose was to cancel out the cumulative effects of gravitation. He later called this, "the biggest blunder of my life".<ref>{{citation |url=https://books.google.com/books?id=UM2agAdvbXkC&pg=PA246 |title=The Quantum World: Quantum Physics for Everyone |author=Kenneth William Ford
 |publisher=Harvard University Press |year=2004 |isbn=9780674037144}}</ref>

== See also ==
* [[Anthropic principle]]
* [[Confidence interval]]
* [[Plug (accounting)]]

== References ==
{{reflist}}

[[Category:Heuristics]]
[[Category:Error]]