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

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

Subject |
RE: st: Ritesh's Inquiry |

Date |
Sat, 5 Jul 2003 22:43:56 +0100 |

Ritesh Mistry asked > >Lets say i have a list of 10 individuals and 10 scores. > For each individual > >I would like to compute a new variable that is the average > of the other 9 > >scores. Any ideas on how that can be done? > > > >The data for the example look like this: > > > >id score newvar > > 1 10 > > 2 13 > > 3 12 > > 4 19 > > 5 21 > > 6 9 > > . > > . > > . > >10 15 > > > >The next problem I am having difficulty with is that these > 10 individuals > >are nested within a community and there are, lets say, 5 > communities in > >total with 10 individual is each for total N of 50. I > would like to compute > >the new variable, where the value for a particular > individual is the average > >of the scores for the other 9 people in the community > where they reside. So > >I would like to repeat the procedure separately for each community. Royce de R. Barondes replied > 1. Create a new variable "score_total" (for the entire > population or, > using "by", the individual community) comprising the sum of > all the scores > (within the population or community). > 2. Generate newvar equal to (score_total-score)/(n-1) Clearly, Royce is correct. You can use the principle sum for everybody else = sum for everybody - value for you after which average for everybody else = sum for everybody else / (n - 1) In Stata terms this is, with a group structure: bysort group : gen newvar = sum(score) by group : replace newvar = newvar[_N] / (_N - 1) There could be at least one problem with this, any missing values in -score-. The extra wrinkle to cope with that is something like bysort group : gen newvar = sum(score) by group : gen N = sum(score < .) by group : replace newvar = newvar[_N] / (N[_N] - 1) or like bysort group : gen newvar = sum(score) by group : egen N = count(score) by group : replace newvar = newvar[_N] / (N - 1) There is a more detailed discussion of this and similar problems at 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 Nick n.j.cox@durham.ac.uk * * 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: Ritesh's Inquiry (correction)***From:*"Nick Cox" <n.j.cox@durham.ac.uk>

**References**:**Re: st: Ritesh's Inquiry***From:*Royce Barondes <BarondesR@missouri.edu>

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