Pre- and post-test probability: Difference between revisions

Revision as of 14:25, 19 January 2014

Revision as of 19:56, 28 January 2014

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*Posttest probability = Posttest odds / (Posttest odds + 1)

[[File:Fagan nomogram.svg|thumb|''Fagan nomogram''<ref>Parameters taken from [http://ard.bmj.com/content/65/10/1301/F4.large.jpg image] in: {{cite journal |author=Zhang W, Doherty M, Pascual E, ''et al.'' |title=EULAR evidence based recommendations for gout. Part I: Diagnosis. Report of a task force of the Standing Committee for International Clinical Studies Including Therapeutics (ESCISIT) |journal=Ann. Rheum. Dis. |volume=65 |issue=10 |pages=1301–11 |yeardate=October 2006 |month=October |pmid=16707533 |pmc=1798330 |doi=10.1136/ard.2006.055251 |url=http://ard.bmj.com/content/65/10/1301.abstract}}</ref>]]

The relation can also be estimated by a so-called ''Fagan nomogram'' (shown at right) by making a straight line from the point of the given ''pre-test probability'' to the given ''likelihood ratio'' in their scales, which, in turn, estimates the ''post-test probability'' at the point where that straight line crosses its scale.