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From |
Nick Cox <n.j.cox@durham.ac.uk> |

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

Subject |
st: RE: calculating mean without own observation |

Date |
Mon, 23 May 2011 16:02:35 +0100 |

This is an FAQ. FAQ . . Creating variables recording prop. of the other members of a group . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . N. J. Cox 4/05 How do I create variables summarizing for each individual properties of the other members of a group? http://www.stata.com/support/faqs/data/members.html Once you know to look for references to (e.g.) "members.html" in the Statalist archive, you can find several related discussions. In this case, something like egen total = total(value), by(category) egen n = count(value), by(category) gen totalMINUSi = total - cond(missing(value), 0, value) gen meanMINUSi = totalMINUSi / (n - !missing(value)) Incidentally, this cannot be done with a simple -if- precisely because values for other observations are involved in the calculation. But it can be approached directly. Nick n.j.cox@durham.ac.uk Guo Xu How do I calculate a mean (or any other summary statistic) excluding the *current* observation? For example, I have following data: i value category 1 5 1 2 5 1 3 10 1 4 2 2 5 2 2 I would like to calculate the mean for each category (egen value_mean = mean(value), by(category)), but exclude the i-th observation: For i=1, for example, the mean value by category 1 would be (5+10)/2. For i=3, it would be (5+5)/2. For i=4, it would be 2/1. I guess there must be some simple *if* condition for this manipulation, but I failed to find it - would be most grateful for help. * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/

**Follow-Ups**:**Re: st: RE: calculating mean without own observation***From:*Nick Cox <njcoxstata@gmail.com>

**References**:**st: calculating mean without own observation***From:*Guo Xu <digitalepourpre@gmail.com>

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