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From |
sjsamuels@gmail.com |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: "time ratios" and "hazard ratios" |

Date |
Thu, 14 May 2009 10:57:40 -0400 |

-- "can I take the multiplicative inverse of the time ratio and report it as a hazard ratio?" No, The (log) Weibull is the only probability distribution for which this is true. It's a good idea to consider multiple probability distributions, as you have done. but reporting the regression results is not enough. Have you evidence that these distributions fit the data? (using a -linktest- or diagnostic plots, for example); that one fits any better or worse than the others? You can compare directly the likelihoods of the log-logistic and log-normal, and those of the log-normal and Weibull models. For hazard ratio models, I rarely see anything but a Cox model these days, because the Weibull has a very restrictive shape. Patrick Royston's -stpm- (from SSC) offers a flexible parametric version. For the log-linear regression models , the generalized Gamma in Stata has the most flexible shape, and its likelihood can be compared directly to those of the Weibull and log-normal. See: Stephen Jenkins's book “Survival Analysis”, available from his website (http://www.iser.essex.ac.uk/teaching/degree/stephenj/ec968/pdfs/ec968lnotesv6.pdf ). -Steve On Wed, May 13, 2009 at 7:16 PM, Emory Morrison <Morrison@soc.msstate.edu> wrote: > I am reporting different specifications of event history models within the same paper. > > In some of the models (for example the log logistic specification and the log normal specification) stata reports coefficients as time ratios. > > In the Weibull model stata report coefficients as hazard ratios. > > While the direction of effects are clearly inverted in these two ways of reporting the coefficients, I need to know if these coefficients are precisely inverse. In other words, can I take the multiplicative inverse of the time ratio and report it as a hazard ratio? > > It would be very helpful in writing up the results of the paper, if the coefficients could be read and interpreted in a standardized fashion. > * * 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**:**AW: st: "time ratios" and "hazard ratios"***From:*"Martin Weiss" <martin.weiss1@gmx.de>

**References**:**st: "time ratios" and "hazard ratios"***From:*"Emory Morrison" <Morrison@soc.msstate.edu>

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