Rich,
  The cenboxplot function uses cenros to estimate the censored values. The 
cenros function requires at least 2 uncensored observations to be able to 
do the regression. The cenros function does issue a warning when there are 
more than 80% censored data, but that is suppressed in cenboxplot.
  Hope this helps.
Dave

Date: Wed, 15 Aug 2012 14:28:54 -0700 (PDT)
From: Rich Shepard <rshepard@appl-ecosys.com>
To: r-help@r-project.org
Subject: [R] NADA package/cenboxplot() method: maximum censored
                 percentage
Message-ID:
 <alpine.LNX.2.00.1208151413240.17434@salmo.appl-ecosys.com>
Content-Type: TEXT/PLAIN; format=flowed; charset=US-ASCII

   One set of data has censored (less-than detection limits) water 
chemistry
concentrations for 80-100% of all observations. My initial trial-and-error
attempts to apply the cenboxplot() method suggests that it has an upper
limit to the percentage of censored observations. I do not see this limit 
in
Dennis Helsel's second edition.

   Has anyone experience plotting censored data and can provide me with 
the
maximum percentage of censored data in a set of observations?

TIA,

Rich


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