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From |
Nick Cox <njcoxstata@gmail.com> |

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

Subject |
Re: st: any idea? |

Date |
Sat, 14 Dec 2013 22:31:56 +0000 |

In addition to Red's helpful suggestions, note that technique for such paired data was discussed in http://www.stata-journal.com/sjpdf.html?articlenum=dm0043 which is publicly accessible. The problem is that the identifiers in Rodrigo's example appear to make little sense. How is Stata expected to know that 1 and 4, 2 and 5, 3 and 6 are paired? Perhaps the structure of the dataset is clearer in practice. If so, basic calculations are just a couple of lines or so. Nick njcoxstata@gmail.com On 14 December 2013 15:33, Red Owl <rh.redowl@liu.edu> wrote: > Rodrigo, > > The following code demonstrates an approach with basic loops. > It could be made more efficient with a different loop > structure, but this approach may be more informative. > > *** BEGIN CODE *** > * Build demo data set. > clear > * Length is capitalized to distinguish from length(). > input id str5(side) Length > 1 right 10 > 2 right 15 > 3 right 11 > 4 left 13 > 5 left 10 > 6 left 12 > end > > gen byte newvar1 = . > forval i = 1/3 { > replace newvar1 = Length[`i'] - Length[4] in `i' > } > forval i = 4/6 { > replace newvar1 = Length[`i'] - Length[1] in `i' > } > > gen byte newvar2 = . > forval i = 1/3 { > replace newvar2 = Length[`i'] - Length[5] in `i' > } > forval i = 4/6 { > replace newvar2 = Length[`i'] - Length[2] in `i' > } > > gen byte newvar3 = . > forval i = 1/3 { > replace newvar3 = Length[`i'] - Length[6] in `i' > } > forval i = 4/6 { > replace newvar3 = Length[`i'] - Length[3] in `i' > } > > list, noobs sep(0) > *** END CODE *** > > Good luck. > > Red Owl > redowl@liu.edu > > >> Y.R.E. Retamal" <yrer2@cam.ac.uk> Sat, 14 Dec 2013 12:08:42: >> >> Dear list >> >> I am very complicated trying to perform an analysis using STATA and I > cannot find the way. Maybe you could help me. I want to create some new > variables containing the difference between the length of two > individuals from different groups: >> >> >> id side length newvar1 newvar2 newvar3 >> 1 right x x-j x-k x-l >> 2 right y y-j y-k y-l >> 3 right z z-j z-k z-l >> 4 left j j-x j-y j-z >> 5 left k k-x k-y k-z >> 6 left l l-x l-y l-z >> >> >> I do not know if I do explain myself clearly, the individuals are > bones (clavicles, for example), so it is possible that some right > clavicles pair-match with left clavicles, following the idea that an > individual has bone of similar length. >> >> Any help could bring me a light! >> Best wishes >> >> Rodrigo > * > * For searches and help try: > * http://www.stata.com/help.cgi?search > * http://www.stata.com/support/faqs/resources/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/faqs/resources/statalist-faq/ * http://www.ats.ucla.edu/stat/stata/

**Follow-Ups**:**Re: st: any idea?***From:*"Y.R.E. Retamal" <yrer2@cam.ac.uk>

**References**:**Re: st: any idea?***From:*Red Owl <rh.redowl@liu.edu>

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