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From |
"Seed, Paul" <paul.seed@kcl.ac.uk> |

To |
"statalist@hsphsun2.harvard.edu" <statalist@hsphsun2.harvard.edu> |

Subject |
Re: st: random uniform variable with unequal probabilities |

Date |
Tue, 20 Nov 2012 10:25:16 +0000 |

On Mon, Nov 19, 2012 at 11:44 AM, TomÃ¡Å¡ HouÅ¡ka <xbender@gmail.com> wrote: > I need to generate a random variable from uniform distribution, but > the probabilities are not not same for each option. The variable is > discrete in interval [10,19] and is generated 10times. Each time one > of the options has twice as high probability of occurring as the > others. So in some sense, the draw is two-staged - in the first stage > a random number (n) between 1 and 10 is generated and then that > particular n-th option in the interval [10,19] has a probability 0.2 > of occurring, the other options have a probability 0.8/9 each. > > How can I generate such variable? Actually, this _is_ a uniform distribution: It can be shown that Pr(X=x) = 0.1 for all integer x in the interval [10,19], = 0 otherwise. So the double negative ("not not same") does for once equal a positive. However, the second sentence implies that what is produced is not a number, but a group of 10 numbers, and the 10^10 possible groups are definitely not all equally likely. I expect that Nick's code can be easily adapted to give blocks of 10 numbers. BW Paul T Seed, Senior Lecturer in Medical Statistics, Division of Women's Health, King's College London Women's Health Academic Centre, King's Health Partners (+44) (0) 20 7188 3642. * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/faqs/resources/statalist-faq/ * http://www.ats.ucla.edu/stat/stata/

**Follow-Ups**:**Re: st: random uniform variable with unequal probabilities***From:*Nick Cox <njcoxstata@gmail.com>

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