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From |
"Gao Liu" <gao.liu@gmail.com> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: One to N matching |

Date |
Tue, 18 Nov 2008 13:04:41 -0500 |

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/

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

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

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