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From |
Richard Goldstein <richgold@ix.netcom.com> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: One to N matching |

Date |
Tue, 18 Nov 2008 13:24:58 -0500 |

Rich Gao Liu wrote:

Thank you, Richard and Autstin, The score in my dataset is actually from psmatch2. Although psmatch2 provides 1 to n matching, but it does not indicate which non-case observations are matched to the case obs, except for the nearest one. Also it allows duplicated matching. That is why I plan to do it by hand. I just checked the command, vmatch. I did not find that it provdes the option of 1 to N matching. Austin, can you decribe some more how to do it by hand. best Gao On Tue, Nov 18, 2008 at 11:32 AM, Austin Nichols <austinnichols@gmail.com> wrote:Gao Liu-- Actually, I think you are looking for -psmatch2- (findit psmatch2). Or did you want to program the matching by hand? That is also possible, and not very hard in the case where all you want is the nearest N matches. However, note that the order of matching will matter in the situation you describe--matching without replacement--so you should probably do the matching many times and compute statistics using the rules of variance computation for multiple imputation. On Tue, Nov 18, 2008 at 11:07 AM, Richard Goldstein <richgold@ix.netcom.com> wrote:for already existing programs, rather than writing your own, I would start with -vmatch- (user-written, type -findit vmatch-) I'm not sure it will cover your last criterion (used only once) but if not it should be easy to eliminate those Rich Gao Liu wrote:Dear Statlist: I have a question about one to N matching. I have a dataset containing three variables: id, score, case, where case is a dummy variable indicating whether or not the observation is in the case group. How can I match each case observation to N non-case observation based on the score? Each case observation matches to the N non-case observations with the closest scores, but no case observation can match the same observation (i.e. the non-case observation can be used only one time). Thank you Best Gao* * 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/

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**Follow-Ups**:**Re: st: One to N matching***From:*"Gao Liu" <gao.liu@gmail.com>

**Re: st: One to N matching***From:*"Austin Nichols" <austinnichols@gmail.com>

**References**:**st: One to N matching***From:*"Gao Liu" <gao.liu@gmail.com>

**Re: st: One to N matching***From:*Richard Goldstein <richgold@ix.netcom.com>

**Re: st: One to N matching***From:*"Austin Nichols" <austinnichols@gmail.com>

**Re: st: One to N matching***From:*"Gao Liu" <gao.liu@gmail.com>

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