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Unformatted text preview: Fitting discrete distributions Discrete distribution A probability distribution describing a discrete numerical random variable For example, Number of heads from 10 flips of a coin Number of flowers in a square meter Number of disease outbreaks in a year ! 2 Goodnessoffit test Compares counts to a discrete probability distribution Hypotheses for ! 2 test H : The data come from a particular discrete probability distribution. H A : The data do not come from that distribution. Test statistic for ! 2 test ! 2 = Observed i Expected i ( ) 2 Expected i all classes # The month of birth for 1245 NHL players Month Number of players January 133 February 125 March 114 April 119 May 119 June 123 July 96 August 91 September 83 October 84 November 73 December 85 A GoodnessofFit test compares count data to a model of the expected frequencies of a set of categories. Hypotheses for birth month example H : The probability of a NHL birth occurring on any given month is equal to national proportions. H A : The probability of a NHL birth occurring on any given month is not equal to national proportions. Month Number of players Expected (%) January 133 7.94 February 125 7.63 March 114 8.72 April 119 8.63 May 119 8.95 June 123 8.57 July 96 8.76 August 91 8.5 September...
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 Spring '10
 Driscoll
 Statistics, Probability

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