Probability mass function: Difference between revisions

Revision as of 04:34, 10 May 2007

Revision as of 23:57, 19 May 2007

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==Mathematical description==

[[Image:Binomial distribution pmf.png|right|thumb|325px|Probability mass function for the [[binomial distribution]] for various parameters. The lines connecting the dots are added for clarity.]]

Suppose that ''X'' is a discrete random variable, taking values on some [[countable]] [[sample space]]  ''S'' ⊆ '''R'''. Then the probability mass function  ''f''_''X''(''x'')  for ''X'' is given by

:<math>f_X(x) = \begin{cases} \Pr(X = x), &x\in S,\\0, &x\in \mathbb{R}\backslash S.\end{cases}</math>