R help - Jun 2011 - nonparametric logistic regression based on locally weighted scatterplot smoothing (lowess)

Dear UseRs:

Recently, I have read an article regarding the association between age and
lymph node metastases.
http://jco.ascopubs.org/content/27/18/2931.long
In statistical analysis, the authors stated "Because a nonlinear
relationship between age and lymph node involvement was expected based on
existing literature, lymph node involvement was also regressed on age using
nonparametric logistic regression based on locally weighted scatterplot
smoothing (lowess)."
<http://jco.ascopubs.org/content/27/18/2931.long#ref-11>
Could someone explain nonparametric logistic regression based on locally
weighted scatterplot smoothing (lowess)?
Or it is nonparametric regression based on locally weighted scatterplot
smoothing (lowess)

Thanks

*Yao Zhu*
*Department of Urology
Fudan University Shanghai Cancer Center
Shanghai, China*

	[[alternative HTML version deleted]]

On Jun 4, 2011, at 11:41 AM, zhu yao wrote:
> Dear UseRs:
>
> Recently, I have read an article regarding the association between  
> age and
> lymph node metastases.
> http://jco.ascopubs.org/content/27/18/2931.long
> In statistical analysis, the authors stated "Because a nonlinear
> relationship between age and lymph node involvement was expected  
> based on
> existing literature, lymph node involvement was also regressed on  
> age using
> nonparametric logistic regression based on locally weighted  
> scatterplot
> smoothing (lowess)."
> <http://jco.ascopubs.org/content/27/18/2931.long#ref-11>
> Could someone explain nonparametric logistic regression based on  
> locally
> weighted scatterplot smoothing (lowess)?
> Or it is nonparametric regression based on locally weighted  
> scatterplot
> smoothing (lowess)
>
One can use a logistic link and a local likelihood. Loader describes  
the advantages of such a strategy and shows a worked example in pages  
60-65 of her text "Local Regression and Likelihood".  But there is no
apparent R content in this question (and the authors of the above  
paper said they used SAS) so this very much off-topic for this list.  
You really should start such requests for explication by addressing  
the authors of the paper. Two other web-based statistical sites for  
general or medical statistics questions can be found at the  
GoogleGroups MedStats group and http://stats.stackexchange.com/ .

-- 
David Winsemius, MD
West Hartford, CT