smooth the ecdf plots

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smooth the ecdf plots

Linda Lei
Hi All,

 

I have codes as follows to get the ecdf plots:

 

 >
day.hos2<-c(6,4,6,6,4,6,5,4,7,5,6,6,8,6,17,9,8,4,6,3,5,8,7,12,5,10,6,4,6
,13,7,6,6,25,4,9,96,6,6,6,6,9,4,5,5,4,10,5,7,6)

 

 >
day.hos3<-c(5,6,7,6,4,5,6,6,6,6,19,7,5,9,8,8,7,5,6,20,40,5,8,7,7,5,6,13,
11,9,4,6,9,16,6,7,6)

 

 > f<-ecdf(day.hos2)

 

 > plot(f,col.p='red',col.h='red')

 

 > g<-ecdf(day.hos3)

 

> lines(g,lty=2)

 

But in order to compare the two ecdf plots. I want to smooth the ecdf
plot, make it like a continuous distribution curve. Could you please

help me with it? I try to find some arguments in "plot" but not
successful.

 

Thank you!


        [[alternative HTML version deleted]]

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Re: smooth the ecdf plots

Bert Gunter
Better idea: Compare directly. ?qqplot

-- Bert Gunter
Genentech Non-Clinical Statistics
South San Francisco, CA
 
"The business of the statistician is to catalyze the scientific learning
process."  - George E. P. Box
 
 

> -----Original Message-----
> From: [hidden email]
> [mailto:[hidden email]] On Behalf Of Linda Lei
> Sent: Thursday, April 20, 2006 10:08 AM
> To: [hidden email]
> Subject: [R] smooth the ecdf plots
>
> Hi All,
>
>  
>
> I have codes as follows to get the ecdf plots:
>
>  
>
>  >
> day.hos2<-c(6,4,6,6,4,6,5,4,7,5,6,6,8,6,17,9,8,4,6,3,5,8,7,12,
> 5,10,6,4,6
> ,13,7,6,6,25,4,9,96,6,6,6,6,9,4,5,5,4,10,5,7,6)
>
>  
>
>  >
> day.hos3<-c(5,6,7,6,4,5,6,6,6,6,19,7,5,9,8,8,7,5,6,20,40,5,8,7
> ,7,5,6,13,
> 11,9,4,6,9,16,6,7,6)
>
>  
>
>  > f<-ecdf(day.hos2)
>
>  
>
>  > plot(f,col.p='red',col.h='red')
>
>  
>
>  > g<-ecdf(day.hos3)
>
>  
>
> > lines(g,lty=2)
>
>  
>
> But in order to compare the two ecdf plots. I want to smooth the ecdf
> plot, make it like a continuous distribution curve. Could you please
>
> help me with it? I try to find some arguments in "plot" but not
> successful.
>
>  
>
> Thank you!
>
>
> [[alternative HTML version deleted]]
>
> ______________________________________________
> [hidden email] mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide!
> http://www.R-project.org/posting-guide.html
>

______________________________________________
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Re: smooth the ecdf plots

Frank Harrell
In reply to this post by Linda Lei
Linda Lei wrote:

> Hi All,
>
>  
>
> I have codes as follows to get the ecdf plots:
>
>  
>
>  >
> day.hos2<-c(6,4,6,6,4,6,5,4,7,5,6,6,8,6,17,9,8,4,6,3,5,8,7,12,5,10,6,4,6
> ,13,7,6,6,25,4,9,96,6,6,6,6,9,4,5,5,4,10,5,7,6)
>
>  
>
>  >
> day.hos3<-c(5,6,7,6,4,5,6,6,6,6,19,7,5,9,8,8,7,5,6,20,40,5,8,7,7,5,6,13,
> 11,9,4,6,9,16,6,7,6)
>
>  
>
>  > f<-ecdf(day.hos2)
>
>  
>
>  > plot(f,col.p='red',col.h='red')
>
>  
>
>  > g<-ecdf(day.hos3)
>
>  
>
>
>>lines(g,lty=2)
>
>
>  
>
> But in order to compare the two ecdf plots. I want to smooth the ecdf
> plot, make it like a continuous distribution curve. Could you please
>
> help me with it? I try to find some arguments in "plot" but not
> successful.
>
>  
>
> Thank you!

Think about keeping them ECDFs and not distorting them.  And you can
superimpose two of them using thin blank lines for one and thicker gray
scale lines for the other and be able to see them clearly.  Use e.g.

library(Hmisc)
?ecdf  (look at groups argument)

Someday I may rename ecdf in Hmisc to avoid confusion with the builtin
ecdf function.

Frank

>
>
> [[alternative HTML version deleted]]
>
> ______________________________________________
> [hidden email] mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
>


--
Frank E Harrell Jr   Professor and Chair           School of Medicine
                      Department of Biostatistics   Vanderbilt University

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Frank Harrell
Department of Biostatistics, Vanderbilt University