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

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

Subject |
st: RE: take the age of one observation and attach it to its matching observation by id with events accruing over time intervals |

Date |
Sun, 18 Oct 2009 17:44:18 +0100 |

Two contributions by Jeph Herrin and Scott Merryman to this thread centred on using a -merge- to merge a subset of the data with the data as a whole. As Eric did not point out that he was using Stata 10.1, the solutions both specified a syntax of -merge- for 11, but he evidently managed to translate back to the old syntax. That's a good solution, but it left up in the air how Eric could have solved his problem using the methods in the sources he quoted. Here's a solution in that style: gen goal = . qui forval i = 1/`=_N' { su age if id == spouse_id[`i'] & year == year[`i'], meanonly if r(min) == r(max) replace goal = r(min) in `i' else replace goal = -999 in `i' } This code does the look-up that is wanted. That is, you want (a) the age of the person who is the spouse of the person in this observation age if id == spouse_id[`i'] but (b) we must look it up for the same year, as spouses come and go & year == year[`i'] There is some built-in paranoia to do some checking. -summarize, meanonly- will, it is evidently hoped, find one observation and thus one valid value for each spouse in each year. In that case, the minimum and maximum returned will be identical. If not, then there is some problem with the data and the code puts -999 in each such observation. (Thus check that there are no -999 values afterwards.) A loop over observations is often disparaged, by myself too, as inefficient, but in problems like this it is close to a relatively transparent way of thinking about the problem. No-one addressed the last part of Eric's post, but marriage durations yield easily to either -tsspell- from SSC or the techniques discussed in SJ-7-2 dm0029 . . . . . . . . . . . . . . Speaking Stata: Identifying spells . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . N. J. Cox Q2/07 SJ 7(2):249--265 (no commands) shows how to handle spells with complete control over spell specification Nick n.j.cox@durham.ac.uk Eric Fail After hours of reading and fiddling around I allow myself to write on the Statalist in the hope that someone out there will take the time to help me. What I want to do seem quite simple but I just can't figure it out. I simply want to take the age of one spouse and attach it to its matching spouse by id, so I get a spouse_age at each observation. I have read this thread http://www.stata.com/statalist/archive/2002-07/msg00124.html where the case is family's, but as I don't have continues id's that tips doesn't seem to work in my case. Furthermore I have read Nicholas J. Cox' Stata tip 51: Events in intervals. But I must admit that I couldn't figure it out from that description either. So now I try my luck here at the Statalist. I have a dataset like the one below, except the 'goal_spouse_age', that's the variable I want to create. clear input str17 date year id spouse_id age goal_spouse_age "01/01/2000" 2000 1 4 40 19 "01/01/2001" 2001 1 4 41 20 "01/01/2002" 2002 1 5 42 40 "01/01/2000" 2000 2 6 24 24 "01/01/2001" 2001 2 7 25 40 "01/01/2000" 2000 3 8 20 16 "01/01/2001" 2001 3 8 21 17 "01/01/2002" 2002 3 11 22 44 "01/01/2003" 2003 3 4 23 22 "01/01/2000" 2000 4 1 19 40 "01/01/2001" 2001 4 1 20 41 "01/01/2002" 2002 5 1 40 42 "01/01/2000" 2000 6 2 24 24 "01/01/2001" 2001 7 2 40 25 "01/01/2000" 2000 8 3 16 20 "01/01/2001" 2001 8 3 17 21 "01/01/2002" 2002 11 3 44 22 "01/01/2003" 2003 4 3 22 23 End Can anyone tell me what to do or what I should read to figure this out? I have managed to count the numbers of spouse each observation has, by using the loop below, thanks to Nicholas J. Cox' description the thread mention above. local N = _N forvalues i = 1/`N' { egen tag = tag(spouse_id) /// if id == id[`i'] count if tag replace count = r(N) in `i' drop tag } The next thing I need to do is to measure the length of the first two or three marriages the observations have had. I mention this even I haven't work very much on this part in the hope that one of you guys out there have had s similar case or can direct me to somewhere where I can read more about the specific case with events accruing over a time span. * * 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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