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{{Use American Englishdate = March 2019}}
{{Short descriptionMeasure of total value one, generalizing probability distributions}}
[[File:MaxwellDistr.pngthumb300pxIn many cases, [[statistical physics]] uses ''probability measures'', but not all [[measure theorymeasures]] it uses are probability measures.<ref name="stern">''A course in mathematics for students of physics, Volume 2'' by Paul Bamberg, Shlomo Sternberg 1991 {{isbn0521406501}} [https://books.google.com/books?id=eSmC4qQ0SCAC&pg=PA802 page 802]</ref><ref name="gut">''The concept of probability in statistical physics'' by Yair M. Guttmann 1999 {{isbn0521621283}} [https://books.google.com/books?id=Q1AUhivGmyUC&pg=PA149 page 149]</ref>]]
{{Probability fundamentals}}
In [[mathematics]], a '''probability measure''' is a [[realvalued function]] defined on a set of events in a [[probability space]] that satisfies [[Measure (mathematics)measure]] properties such as ''countable additivity''.<ref>''An introduction to measuretheoretic probability'' by George G. Roussas 2004 {{isbn0125990227}} [https://books.google.com/books?id=J8ZRgCNSwcC&pg=PA47 page 47]</ref> The difference between a probability measure and the more general notion of measure (which includes concepts like [[area]] or [[volume]]) is that a probability measure must assign value 1 to the entire probability space.
