R help - Oct 2009 - Kolmogorov smirnov test

Hi r-users,
 
I would like to use Kolmogorov smirnov test but in my observed data(xobs) there
are ties.  I got the warning message.  My question is can I do something about
it?
 
ks.test(xobs, xsyn)
 
        Two-sample Kolmogorov-Smirnov test
data:  xobs and xsyn 
D = 0.0502, p-value = 0.924
alternative hypothesis: two-sided 

Warning message:
In ks.test(xobs, xsyn) : cannot compute correct p-values with ties
 
Thank you for all your help.



      
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Hi Roslina,

I believe that you can ignore the warning.
Alternatively, you may add a very small random noise to pairs with ties, i.e.
something like
xobs[which(duplicated(xobs))] <- xobs[which(duplicated(xobs))] +
1.0e-6*sd(xobs)*rnorm(length(which(duplicated(xobs))))

Regards,

Moshe.

--- On Tue, 13/10/09, Roslina Zakaria <zroslina at yahoo.com> wrote:
> From: Roslina Zakaria <zroslina at yahoo.com>
> Subject: [R] Kolmogorov smirnov test
> To: r-help at r-project.org
> Received: Tuesday, 13 October, 2009, 9:58 AM
> 
> Hi r-users,
> ?
> I would like to use Kolmogorov smirnov test but in my
> observed data(xobs) there are ties.? I got the warning
> message.? My question is can I do something about it?
> ?
> ks.test(xobs, xsyn)
> ?
> ??????? Two-sample Kolmogorov-Smirnov test
> data:? xobs and xsyn 
> D = 0.0502, p-value = 0.924
> alternative hypothesis: two-sided 
> 
> Warning message:
> In ks.test(xobs, xsyn) : cannot compute correct p-values
> with ties
> ?
> Thank you for all your help.
> 
> 
> 
> ? ? ? 
> ??? [[alternative HTML version deleted]]
> 
> 
> -----Inline Attachment Follows-----
> 
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