R help - Sep 2006 - Stats question - cox proportional hazards adjustments

Hi useRs,

Many studies of the link between red meat and colorectal cancer use
Cox proportional
hazards with (among other things) a gender covariate.

If it is true that men eat more red meat, drink more alcohol and smoke more than
women, and if it is also true that alcohol and tobacco are known risk
factors then why does
it make sense to "adjust" for gender?   I would think that in this
case some of the
risk that should be properly attributed to the bad habits will actually end
up being attributed to being male instead.


Cheers,
Geoff Russell

"Geoff Russell" <geoffrey.russell at gmail.com> writes:
> Hi useRs,
> 
> Many studies of the link between red meat and colorectal cancer use
> Cox proportional
> hazards with (among other things) a gender covariate.
> 
> If it is true that men eat more red meat, drink more alcohol and smoke more
than
> women, and if it is also true that alcohol and tobacco are known risk
> factors then why does
> it make sense to "adjust" for gender?   I would think that in
this
> case some of the
> risk that should be properly attributed to the bad habits will actually end
> up being attributed to being male instead.
This is more than a bit off-topic for the list, but in (very) brief:
Because you need to get rid of purely gender related effects that
disturb the analysis and may create spurious association.

Otherwise you would become able to "prove" effects like stiletto heels
causing breast cancer, etc. 

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