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From |
Phil Clayton <philclayton@internode.on.net> |

To |
statalist@hsphsun2.harvard.edu |

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

Date |
Tue, 24 May 2011 00:25:50 +0930 |

I'm sure there's a more efficient way but one option would just be to loop over the observations manually and calculate the mean each time: clear input i value category 1 5 1 2 5 1 3 10 1 4 2 2 5 2 2 end gen value_mean=. forval i=1/`=_N' { summarize value if category==category[`i'] & _n!=`i', meanonly quietly replace value_mean=r(mean) in `i' } list Phil On 24/05/2011, at 12:02 AM, Guo Xu wrote: > Dear Stata list, > > 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. > > Thanks, > > Guo > * > * 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/ * * 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/

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

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