[R] odds ratio per standard deviation

[David Winsemius]

On Jun 12, 2013, at 4:58 PM, vinhnguyen04x wrote:

> L. Snow,
> Ted,
> 
> Many thanks, I am sorry to made a question without context. I use three
> parameters of facial temperature, heart rate, and respiratory rate to
> distinguish infectious patients from healthy subjects. So I use logistic
> regression to generate a classification model and calculate the odds ratio
> for these three parameters. In my case, I would like to know what kinds of
> odds ratio can be used, odds ratio per standard deviation or odds ratio. 
> 
> Thanks you in advance for your help
> 

The answer will depend on the distribution of the covariates, about which you have offered no information. It may also depend on what would be considered a relevant distance along the covariate "axes" by your audience. Generally odds ratios comparing a single year of increased age are not very interesting, but a difference of a decade will be understood by most audiences. Frank Harrell's rms/Hmisc package displays differences comparing the interquartile range. For heart rate I would think comparing a value of 80 to a value of 81 would nnot be thought of as clinically relevant. Most people are not capable of transforming odds ratios presented for a single unit difference to ones comparing a ten unit contrast. Differences of a degree of facial temperature might be more sensible given the narrow range over which temeperatures are maintained.  It is your responsibility to make these decisions based on domain knowledge. Any knowledgeable practitioner of statistics can make transformation to another contrast if enough digits of accuracy are offered. (It is rather frustrating to see published comparisons for single units of difference presented with minimal accuracy.)

-- 

David Winsemius
Alameda, CA, USA