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From |
"Tony Brady" <tony@sealedenvelope.com> |

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

Subject |
st: Re: obtaining statistics from clustered data |

Date |
Wed, 26 Jun 2002 21:03:19 +0100 |

Interesting question... my solution is to use egen within a loop that omits each observation in turn from the cluster. In this code I'm averaging sbp within clusters defined by id. Obviously substitute in your own variable names for id, sbp and msbp (the variable that ends up with your statistic of interest). sort id by id: gen rank=_n summ rank local hirank=r(max) gen msbp=. foreach i of numlist 1/`hirank' { egen temp=mean(sbp) if rank!=`i', by(id) by id: replace msbp=temp[_N] if rank==`i' & `i'<_N by id: replace msbp=temp[1] if rank==`i' & `i'==_N drop temp } drop rank You can change the egen line to, for instance, egen temp=sd(sbp)... if you want standard deviations instead of means or any other statistic offered by egen. Using egen isn't an elegant solution but it does offer some flexibility and avoids the need to write lots of code. Tony ___________________ Tony Brady Sealed Envelope Ltd > Date: Tue, 25 Jun 2002 22:30:54 -0500 > From: "Javier Escobal" <jescobal@grade.org.pe> > Subject: st: programming question: obtaining statistics from clustered data > > Dear Stata listers > > I need to construct a number of summary statistics for clustered data > with a particular twist: for each observation the summary statistics > should be constructed without taking into the account the reference > observation. > > I have a data base that has the following form: > > id cluster X > 1 1 0.5 > 2 1 0.7 > 3 1 0.4 > . . . > . . . > . . . > 100 3 0.6 > 101 3 0.6 > 102 3 0.8 > 103 3 0.2 > > that is observations can be grouped in clusters (of different size). I > am interested in constructing different statistics: for example for each > observation "i" I need to capture the average and standard deviation of > all observations that belong to the same cluster where "i" belongs > excluding observation "i". > > Can somebody help me with a simple way of constructing this aggregates? > > I appreciate the response > > Javier > > > * > * 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/ > > ------------------------------ > > End of statalist-digest V4 #927 > ******************************* > > * > * 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/ * * 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/

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