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In [[baseball]], '''wOBA''' (or '''weighted on-base average''') is a statistic, based on [[linear regression|linear weights]], designed to measure a player's overall offensive contributions per plate appearance.  It is formed from taking the observed run values of various offensive events, dividing by a player's plate appearances, and scaling the result to be on the same scale as [[on-base percentage]].  Unlike statistics like [[On-base plus slugging|OPS]], wOBA attempts to assign the proper value for each type of hitting event.  It was created by [[Tom Tango]] and his coauthors for ''The Book: Playing the Percentages in Baseball.''<ref name="thebook">http://www.insidethebook.com/woba.shtml</ref>

== Usage ==
In 2008, [[sabermetrics]] website [[FanGraphs]] began listing the current and historical wOBA for all players in [[Major League Baseball]].<ref>http://www.fangraphs.com/blogs/index.php/the-joy-of-woba/</ref>  It forms the basis of the offensive component of their [[Wins above replacement]] (WAR) metric.  Sites such as [[The Hardball Times]] have studied wOBA and found it to perform comparably to or better than other similar tools (OPS, [[Runs created]], etc.) used in sabermetrics to estimate runs.<ref>http://www.thehardballtimes.com/main/article/the-great-run-estimator-shootout-part-1/</ref><ref>http://www.thehardballtimes.com/main/article/the-great-run-estimator-shootout-part-2/</ref>  ''The Book'' uses wOBA in numerous studies to test the validity of many aspects of baseball conventional wisdom.

==Formula==
The formula, as it originally appeared in ''The Book,'' is

<math>wOBA=\frac{(0.72*NIBB) + (0.75*HBP) + (0.90*\mathit{1}B) + (0.92*RBOE) + (1.24*\mathit{2}B) + (1.56*\mathit{3}B) + (1.95*HR)}{PA}</math>

where:
*''NIBB'' = Non-intentional [[Base on balls|bases on balls]]
*''HBP'' = [[Hit by pitch]]
*''1B'' = [[Single (baseball)|Single]]
*''RBOE'' = Reached base on [[Error (baseball)|error]]
*''2B'' = [[Double (baseball)|Double]]
*''3B'' = [[Triple (baseball)|Triple]]
*''HR'' = [[Home run]]
*''PA'' = [[Plate appearance]]

== Citations ==
<!--- See http://en.wikipedia.org/wiki/Wikipedia:Footnotes on how to create references using <ref></ref> tags which will then appear here automatically -->
{{Reflist}}

== References ==
*[[Tom Tango]], Mitchel Lichtman, and Andrew Dolphin. ''The Book: Playing the Percentages in Baseball''. Washington, D.C.: Potomac Books, 2007. ISBN 1-59797-129-4.

{{Baseball statistics}}

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[[Category:Batting statistics]]


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