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From |
Austin Nichols <austinnichols@gmail.com> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: st: Handling age in Hazard Ratios |

Date |
Mon, 4 Jun 2012 15:25:39 -0400 |

Clifton Chow <clifton_chow@post.harvard.edu>: Maximum, eh? tw function ln(.9299)*x+ln(1.0007)*x^2, ra(0 80) xla(52) On Mon, Jun 4, 2012 at 2:24 PM, Clifton Chow <clifton_chow@post.harvard.edu> wrote: > I got it from Wooldridge, p. 193. It's just the maximum. > > >> -------Original Message------- > > Where did you get the algebra suggesting that .9299/2*1.0007 represents the turning point? > di ln(.9299)/(2*ln(1.0007)) > >> From: Clifton Chow <clifton_chow@post.harvard.edu> >> To: statalist@hsphsun2.harvard.edu >> Subject: st: Handling age in Hazard Ratios >> Sent: 04 Jun '12 12:46 >> >> I ran a proportional hazards model on the duration of employment and had as my covariates, age and age^2, respectively. The coefficients and hazard ratios for both variables are below: >> >> Coefficient: Age = -.0727 >> Age^2 = .0007 >> >> Hazard Ratio: Age = .9299 >> Age^2 = 1.0007 >> >> I am trying to interpret the diminishing effect of the quadratic term by calculating the age at which the risk changes from a decrease to ian ncrease risk of job loss. I did this by dividing the age coefficient by 2 * age^2 coefficient. However, when performing this calculation on the raw coefficient, the age of change is 52 (.0727/2*.0007) but in the hazard ratios, that age is 46 (.9299/2*1.0007). Does anyone know which convention to report? I think the difference of 5 years between the two sets of coefficients are important, right? * * 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/

**References**:**st: st: Handling age in Hazard Ratios***From:*"Clifton Chow" <clifton_chow@post.harvard.edu>

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