Loess standard error curves

[Eduardo Nogueira <nogueira@hc.unicamp.br>]

Dear Splus users

On a trellis graphic, I plotted   loess smooth curves of blood
pressure along time conditioned by the presence of age(4 levels)  and
hypertension (2 levels): 


xyplot(pressure~time|hypertension,data=data1,layout=c(4,2,1),
       panel=function(x,y){
         panel.xyplot(x,y )
         panel.loess(x,y,span=0.25) })

Is it possible to  add (superpose)  the standard error curves of the loess fit 
to this graphic?


Thanks

Eduardo
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Eduardo A Nogueira, MD, PhD
Cardiac Catheterization Laboratory
University of Campinas Medical School