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From |
Maarten buis <maartenbuis@yahoo.co.uk> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: Measure of Variability in a Nominal Variable |

Date |
Mon, 3 Mar 2008 21:30:47 +0000 (GMT) |

--- Kevin Daley <kevin.daley@mail.mcgill.ca> wrote: > I would like to ask if anyone can identify and/or tell me how to > run a certain descriptive statistic in Stata. I am working with a > nominal variable and would like to provide some indication of the > variability within the sample along this variable. I would like to > use a statistic discussed by Agresti in his categorical data analysis > book that gives the probability that two randomly selected > independent observations in a given dataset will end up in different > categories of the given variable. The statistic has a minimum value > of 0 and a maximum value of J-1. Can anyone tell me what this > descriptive statistic is called? More importantly, can anyone tell > me the order needed to run it in Stata? Thank you very much, Kevin. If it is a probability than the maximum is 1. In that case you could compute it as follows: *---------- begin example ------------- sysuse auto, clear preserve contract rep78 , percent(p) nomiss gen double psq = (p/100)^2 sum psq, meanonly di 1-r(sum) restore *--------- end example ----------------- (For more on how to use examples I sent to the Statalist, see http://home.fsw.vu.nl/m.buis/stata/exampleFAQ.html ) Given your description of the maximum I suspect this is not what you are after. Maybe you are looking for the entropy? Hope this helps, Maarten ----------------------------------------- Maarten L. Buis Department of Social Research Methodology Vrije Universiteit Amsterdam Boelelaan 1081 1081 HV Amsterdam The Netherlands visiting address: Buitenveldertselaan 3 (Metropolitan), room Z434 +31 20 5986715 http://home.fsw.vu.nl/m.buis/ ----------------------------------------- __________________________________________________________ Sent from Yahoo! Mail. A Smarter Inbox. http://uk.docs.yahoo.com/nowyoucan.html * * For searches and help try: * http://www.stata.com/support/faqs/res/findit.html * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/

**Follow-Ups**:**Re: st: Measure of Variability in a Nominal Variable***From:*Maarten buis <maartenbuis@yahoo.co.uk>

**References**:**st: Measure of Variability in a Nominal Variable***From:*"Kevin Daley" <kevin.daley@mail.mcgill.ca>

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