Changeset 20604 in project
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 10/03/10 12:39:52 (10 years ago)
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wiki/eggref/4/statistics
r20603 r20604 11 11 To use this library, you need to understand the underlying statistics. In brief: 12 12 13 The [[http://en.wikipedia.org/wiki/Binomial_distributionBinomial distribution]] is used when counting discrete events in a series of trials, each of which events has a probability p of producing a positive outcome. An example would be tossing a coin {{n}} times: the probability of a head is {{p}}, and the distribution gives the expected number of heads in the {{n}} trials. 14 15 The [[http://en.wikipedia.org/wiki/Poisson_distributionPoisson distribution]] is used to count discrete events which occur with a known average rate. A typical example is the decay of radioactive elements. 16 17 The [[http://en.wikipedia.org/wiki/Normal_distributionNormal distribution]] is used for realvalued events which cluster around a specific mean with a symmetric variance. A typical example would be the distribution of people's heights. 13 The [[http://en.wikipedia.org/wiki/Binomial_distributionBinomial distribution]] is used when counting discrete events in a series of trials, each of which events has a probability p of producing a positive outcome. An example would be tossing a coin {{n}} times: the probability of a head is {{p}}, and the distribution gives the expected number of heads in the {{n}} trials. The binomial distribution is defined as B(n, p). 14 15 The [[http://en.wikipedia.org/wiki/Poisson_distributionPoisson distribution]] is used to count discrete events which occur with a known average rate. A typical example is the decay of radioactive elements. A poisson distribution is defined Pois(mu). 16 17 The [[http://en.wikipedia.org/wiki/Normal_distributionNormal distribution]] is used for realvalued events which cluster around a specific mean with a symmetric variance. A typical example would be the distribution of people's heights. A normal distribution is defined N(mean, variance). 18 18 19 19 == Provided Functions … … 238 238 returns the cumulative distribution function (CDF) of the standard normal distribution. 239 239 > (doec (: x 2 2 0.4) 240 (format #t "~4,1f ~,4f~&" x (phi x)))240 (format #t "~4,1f ~,4f~&" x (phi x))) 241 241 2.0 0.0228 242 242 1.6 0.0548
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