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From |
"Martin Weiss" <martin.weiss1@gmx.de> |

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

Subject |
st: AW: RE: Problem looping over spells for an individual |

Date |
Wed, 25 Feb 2009 18:27:39 +0100 |

<> I was desperate to find an SJ tip for Ilona on the difference between "if" and "if"; turns out it is an FAQ: http://www.stata.com/support/faqs/lang/ifqualifier.html HTH Martin -----Ursprüngliche Nachricht----- Von: owner-statalist@hsphsun2.harvard.edu [mailto:owner-statalist@hsphsun2.harvard.edu] Im Auftrag von Nick Cox Gesendet: Mittwoch, 25. Februar 2009 18:22 An: statalist@hsphsun2.harvard.edu Betreff: st: RE: Problem looping over spells for an individual Unless you are working under the aegis of -by:- _N will always be interpreted as the total number of observations. This code doesn't satisfy that. I echo Martin Weiss in suspecting that your -if `touse'- is a bug. You are almost certainly confusing the two flavours of -if-. Otherwise, your code still looks very confused and based on a variety of misunderstandings. Apart from `touse', which is defined by -marksample-, all of the local macros you refer to will be treated as empty strings, as none has been defined earlier in the program. I am surprised to hear that it is running at all. It does not look as if you need a program anyway. My impression is that all you need is to use -by:- but I don't understand your problem well enough to suggest better code. Someone else may be able to give better help. If not, rather than a lengthy word description, you should perhaps give an example of your data with the intended result. Nick n.j.cox@durham.ac.uk Ilona Carneiro I am trying to write a programme that will run a command sequentially for observations of an individual. For each individual I have multiple spells and multiple failures. However, the twist is that I also need to exclude a period of time at risk after each treatment (prophylaxis) and after each failure (to prevent double-counting of failures that may actually be the same episode). I managed to do this without any problem for the treatment, but if an episode is disqualified (by a prior treatment or episode) I don't want it to disqualify a subsequent episode. Therefore I need to run the code sequentially for each spell of an individual, but using the marksample touse code to run it "by" individual doesn't seem to be working - the "forvalues" seems to always interpret _N as the last observation in the whole dataset, not the last observation for each individual. I have the following code: program define byid, byable(recall, noheader) marksample touse sort `id' `start' if `touse' { forvalues i = 1(1)`=_N' { replace lagend = (`end' + `lag') if ((`tx' > 0 & `tx' < .) | (`case' > 0 & `case' < .)) drop if lagend[`i'-1]>`end' & `id'[`i'-1]==`id' } } end gen lagend=. qui by id: byid but I get the error: 2nd by group not found r(111); And the programme isn't doing what I need it to. * * 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: AW: RE: Problem looping over spells for an individual***From:*Ilona Carneiro <ilonac@orange.es>

**References**:**st: Problem looping over spells for an individual***From:*Ilona Carneiro <ilonac@orange.es>

**st: RE: Problem looping over spells for an individual***From:*"Nick Cox" <n.j.cox@durham.ac.uk>

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