[R] imputation of sub-threshold values

[Simon Fear]

> -----Original Message-----
> From: Jonathan Williams
> [mailto:jonathan.williams at pharmacology.oxford.ac.uk]
> Sent: 15 March 2004 12:48
> To: Ethz. Ch
> Subject: [R] imputation of sub-threshold values
> 
> 
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>  
> Is there a good way in R to impute values which exist, 
> but are less than the detection level for an assay?
> Thanks,
> 

There's no failsafe way to do this in ANY language. Imputing
using the value of the detection level, or half way between
there and zero (for strictly positive parameters) are two
methods commonly used in the pharma industry, if the
proportion of results below detection level is small.  
 
Simon Fear 
Senior Statistician 
Syne qua non Ltd 
Tel: +44 (0) 1379 644449 
Fax: +44 (0) 1379 644445 
email: Simon.Fear at synequanon.com 
web: http://www.synequanon.com 
  
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