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Re: st: st: Handling age in Hazard Ratios
From
Austin Nichols <[email protected]>
To
[email protected]
Subject
Re: st: st: Handling age in Hazard Ratios
Date
Mon, 4 Jun 2012 15:25:39 -0400
Clifton Chow <[email protected]>:
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
<[email protected]> 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 <[email protected]>
>> To: [email protected]
>> 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?
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