NADA for R
R is a free and freely-available implementation of the S-language for statistical computing originally developed by John Chambers and others at Bell Labs. It has a Unix-like interface, but compiled versions run under the Unix, Windows and Macintosh operating systems. It is a powerful environment for statistical computing -- newly-developed methods are frequently released with an R implementation. R operates under the GNU license and contributed packages are developed by volunteers worldwide.

NADA for R is a user-contributed package available from the CRAN (Comprehensive R Archive Network) site. It implements the procedures found in the textbook Nondetects And Data Analysis by Helsel (2005) and published by Wiley. Methods are included for computing descriptive statistics, hypothesis tests, correlation and regression for left-censored (nondetect) data

NADA for R can be downloaded and installed from within R using the install.packages command. It is updated regularly, so check for and download the most current version from within your R software. A user's guide to NADA for R is available on our NADA downloads page. The guide is the handout from our August 2006 NADA for R workshop for the American Statistical Association. Through example exercises, the use of the NADA for R package is demonstrated. Datasets used in the exercises come with the NADA for R package, so you can perform each exercise yourself to become familiar with all the NADA for R parametric and nonparametric functions.

Go to the CRAN site (then click on "Packages" at the left side)