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From |
asb stata <asb.stata@gmail.com> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: R: Survival Data - Compare hazards by matching on age (flag: Stata 9.2/SE) |

Date |
Tue, 9 Mar 2010 14:30:51 -0500 |

Carlo, I think the trick is to compare survivors of the same age across the two groups. Let me explain: In group 1, subjects are sure to survive till a certain age unlike in group 2 where they are at risk since age 1. Suppose there are 100 subjects in group 1 and they all survive till age 3 and then some, say ten, come under risk and five die and 95 go on to age 4. Suppose there are another 100 in group 2 and they start dying right away and only 50 survive at the beginning of age 3 and another 10 die and 40 go on to age 4. Among survivors of age 3 across the two groups, 95% survive in group 1 (95 survive among 100) and 80% survive in group 2 (40 survive among 50). I want to plot these percentages of survivors at each age for the two groups. The data is in multiple-records-per-subject format as shown below. The important variable is flag which identifies when a subject in group 1 becomes at risk. Subject id=1 is not at risk until period 2. I need to know how to stset and also how to sts graph. Something like: stset age, id(id) failure(died=1) sts graph, by(group) ........? asb On Tue, Mar 9, 2010 at 11:25 AM, Carlo Lazzaro <carlo.lazzaro@tin.it> wrote: > Asb stata wrote: > "I want to compare the hazard of exit for the two > groups by comparing subjects of the same age across groups. How do I do it > in stata?" > > The following: > - sts test group, logrank strata(age) - > > may do the trick. > > Kind Regards, > Carlo > > -----Messaggio originale----- > Da: owner-statalist@hsphsun2.harvard.edu > [mailto:owner-statalist@hsphsun2.harvard.edu] Per conto di asb stata > Inviato: martedě 9 marzo 2010 8.02 > A: statalist@hsphsun2.harvard.edu > Oggetto: st: Survival Data - Compare hazards by matching on age > > There are two groups of subjects in my data. In the first group, all > subjects are at risk of dying since age 1. In the second group, each > subject > becomes at risk of dying from a subject-specific age different from 1. I > want to stset the data properly and graph Kaplan-Meier survival curves for > the two groups. A sample of data is presented below. id is unique subject > id. group is 1 if subjects do not become at risk of dying until flag=1. > Subject 1 becomes at risk of dying only at age 2 or after unlike subjects 3 > and 4 which become at risk of dying at age 1. died indicates the actual > failure event. The data is set as multiple-record-per-subject. I do not > want > to compare the hazard of exit of the two groups without taking into account > the fact that the members of the first group do not become at risk until a > certain (variable) age. I want to compare the hazard of exit for the two > groups by comparing subjects of the same age across groups. How do I do it > in stata? How to match subjects by age and compare hazard of exit? Is there > another way besides matching on age? > > id group flag age died > 1 1 0 1 0 > 1 1 1 2 0 > 1 1 1 3 0 > 1 1 1 4 1 > 2 1 0 1 0 > 2 1 0 2 0 > 2 1 0 3 0 > 2 1 0 4 0 > 2 1 1 5 0 > 2 1 1 6 1 > 3 2 1 1 0 > 3 2 1 2 0 > 3 2 1 3 1 > 4 2 1 1 0 > 4 2 1 2 0 > 4 2 1 3 0 > 4 2 1 4 0 > 4 2 1 5 1 > > * > * 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/ > * * 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: R: Survival Data - Compare hazards by matching on age (flag: Stata 9.2/SE)***From:*asb stata <asb.stata@gmail.com>

**References**:**st: Survival Data - Compare hazards by matching on age***From:*asb stata <asb.stata@gmail.com>

**st: R: Survival Data - Compare hazards by matching on age (flag: Stata 9.2/SE)***From:*"Carlo Lazzaro" <carlo.lazzaro@tin.it>

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