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From |
"Eric G. Wruck" <ewruck@econalytics.com> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: how to generate sum of distinct id1, by id2, in the lastn years |

Date |
Tue, 18 Sep 2007 10:58:46 -0400 |

Hi Pierre: I started to work on this but then realized I don't understand your data & problem properly. In 1972 we see that star author 1 wrote a paper w. joe 2 & wrote zero papers w. joe 3. Presumably too star author 1 wrote zero papers w. joes 4 & 5, although there is no observation saying so. So, I don't understand how in your desired output you expect to get stk_nbcoauth_it (what does this mean?) = 2 for 1972. Also, 1975 only appears once in your data (3 papers written w. joe 2) but in your desired output, stk_nbcoauth_it = 2 -- please explain. Lastly, you mention something about performing the summing over the last three years -- what does that mean here? Later, Eric >Dear Statalisters, > >I have what I believe a simple programming question that I can't quite solve. >I have a panel of dyads, where each member of the dyad is a coauthor. >Each dyad is composed or a "superstar" and a "simple joe/jane." > >For instance: > >star_id id year nbpapers >--------------------------------------------------------- >1 2 1972 1 >1 2 1973 0 >1 2 1974 2 >1 2 1975 3 >1 2 1976 0 >1 2 1977 4 >1 3 1970 1 >1 3 1971 0 >1 3 1972 0 >1 3 1973 2 >1 4 1978 2 >1 4 1979 1 >1 5 1977 4 >1 5 1978 1 >1 5 1979 0 >1 5 1980 1 >1 5 1981 1 > >So superstar #1 has 4 "simple joe collaborators" numbered 2,3,4, and 5. >In each year, the data records how many publications exist for >superstar i and simple joe/jane j. > > >I would like to collapse this data at the superstar/year level and >create a variable that records the sum of distinct "simple joes" in >the last 3 years. >In other words, I'd like to create the variable stk_nbcoauth_it that is: > >star_id year stk_nbcoauth_it >--------------------------------- >1 1970 1 >1 1971 1 >1 1972 2 >1 1973 2 >1 1974 2 >1 1975 2 >1 1976 1 >1 1977 2 >1 1978 3 >1 1979 3 >1 1980 2 >1 1981 2 > >I have fiddle with bysort star_id id (year), but without clear >success. Could anyone help? > >Regards, > >Pierre > > > >-------------------------------------------------------------------- >Pierre Azoulay >Assistant Professor of Strategy >Massachusetts Institute of Technology >Sloan School of Management >50 Memorial Drive - E52-555 >Cambridge, MA 02142-1947 > >Tel [Sloan]: (617) 258-9766 >Tel [NBER]: (617) 588-1464 >Fax: (617) 253-2660 > -- =================================================== Eric G. Wruck Econalytics 2535 Sherwood Road Columbus, OH 43209 ph: 614.231.5034 cell: 614.330.8846 eFax: 614.573.6639 eMail: ewruck@econalytics.com website: http://www.econalytics.com ==================================================== * * 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/

**References**:**st: how to generate sum of distinct id1, by id2, in the last n years***From:*"Pierre Azoulay" <pierre.azoulay@gmail.com>

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