Nondetects And Data Analysis

The Online Training Course

NADA is a 13-section course. It starts at how to store data with nondetects in databases, moves on to summary statistics and (confidence, tolerance etc.) intervals, then testing differences between groups of data, then regression, trend analysis, and multivariate methods. All without fabricating numbers like 1/2 the detection limit for nondetects. Below are all the course materials we have offered for several years, now with two differences.
1. Everything is now free.
2. There is no personal help from the instructor available.

The course uses R statstical software. Examples are worked in the videos for each section. Exercises are available for you to test how well you've understood the material, and solutions provided for each exercise so that you can check your work. Several hundred students have completed this course. Follow the instructions, download the materials, and enjoy and be challenged by the course!
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Why Take This Course?

To answer that question view the video
The Cost of Complacency
on our Videos page.
Dennis Helsel (PhD in Environmental Science and Engineering, Virginia Tech) has over 40 years experience in applying statistical methods to environmental sciences. He has authored articles in numerous journals, including papers on handling nondetect data such as “More Than Obvious” (ES&T 2005) and "Much Ado About Next to Nothing" (Ann. Occ. Hygiene, 2010). Dr. Helsel has authored Statistics for Censored Environmental Data using Minitab and R (Wiley, 2012), the optional textbook for this course. Dr. Helsel is the 2018 recipient of the Lifetime Acheivement Award from the California Groundwater Resources Association, and a 2003 recipient of the Distinguished Service Award from the American Statistical Association's section on Statistics and the Environment.
Course Outline By Section
Section 1. Get Started with RStudio
Section 2. Detection and Reporting Limits
Section 3. Store Censored Data in Databases
Section 4. Plot Data with Nondetects
Section 5. Estimating Descriptive Statistics
Section 6. Intervals (Confidence, Prediction, Tolerance)
Section 7. Matched Pair Tests & Comparing Data to Standards

If you would like to see NADA2 functions in action to know more about what you can do with NADA2 you can download the exercises pdf from our course here:
NADA2 Solutions to Exercises vers. 3.8 (pdf)
or download the Vignette for the NADA2 package here:
NADA2 package CRAN site

Section 8. Two-Group Tests with Nondetects
Section 9. Three+ Group Tests with Nondetects
Section 10. Correlation and Regression with Nondetects
Section 11. Trend Analysis with Nondetects
Section 12. Logistic Regression
Section 13. Multivariate Methods with Nondetects
1. Get Started
Welcome to the NADA course! Click to download the Welcome to NADA introduction letter. It will give you the roadmap for getting started with our course.
Welcome to NADA.pdf

Then download and install the software needed for the course (R, packages for R, and RStudio). Installation instructions are below. Choose either the Windows or MacOS version. Then follow the instructions to install two software programs, R and RStudio, onto your computer (or give these instructions to your IT staff if you do not have access rights to do the installation).
Installing R for NADA (Windows) blank_spacer Installing R for NADA (Mac)
Download the zip file of course materials. These include all the data, Powerpoint lecture slides and handouts for the class. Unzip and place into a directory that you have full access to, such as your Documents folder. Version 3.9 has a new version of the Zinc dataset which is easier for RStudio to import correctly.
NADA Online

Now watch the two videos below and follow along using your computer to get started with RStudio. You will find pdf files of the Powerpoint slides for all videos in the Lecture Notes directory of your course materials.
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Things To Remember

Videos occasionally mention "NADA scripts", which was a pre-release version of the NADA2 package you have loaded. No extra scripts are needed. Consider all references to NADA scripts as referencing the NADA2 package. No extra scripts are included in the course materials. No loading of extra scripts is required. All you need is the NADA2 package.
Video 1: Getting Started
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Video 1b: Getting Started Computer Demo
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To proceed with the rest of the course you first must register. If you have not yet registered for the course, register here using your name and email address. An email will be sent to you with a password. After receiving that you will be able to login to all of the following pages containing the NADA course.
If you have already registered, please login below.

If you have previously registered but did not receive an email with your password, go to the login area below and enter your email address, then click "
Forgot password?" You'll receive an email with a new password. Click "Acitvate" in the email to begin using this password from then on.

Forgot password?
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Online at:

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