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Measurements of trace chemicals in environmental media (water, air, soils, biota) frequently result in values reported only as less than several laboratory reporting limits ("less-thans", "nondetects", or "qualified values"). Statisticians call these "censored data". Methods specifically designed for interpreting censored data, but rarely taught in classes on environmental statistics, can be used to compute summary statistics, perform hypothesis tests, and compute regression models.

Methods for fully extracting the information contained in data with nondetects will be introduced. The methods explicitly handle data with multiple detection limits. They can directly incorporate ‘qualified' values between detection and quantitation limits. Means and medians can be computed, hypotheses tests performed, and regression equations calculated without substituting any values for nondetects. This seminar introduces methods from the author's textbook Nondetects And Data Analysis: Statistics for censored environmental data, published in 2005 by John Wiley.

Webinar Objectives and Highlights:

  • Methods for handling nondetect data without substituting numbers
  • Handling ‘qualified' values between detection and reporting limits
  • Software that performs methods for censored data
  • Standard methods in other disciplines that could become standard in environmental applications

What You Will Learn:

  • You will know of standard procedures for handling nondetect data without substituting values for them
  • You will see how ‘qualified' values can be incorporated without just dropping the ‘E' or ‘J' qualifier and treating them as detected values
  • You will see these methods performed with software
  • You will know of methods for handling data with multiple detection limits that actually work well.

Whether you want to learn more about statistical methods or managing detection limits, this webinar will provide participants with information that is not available elsewhere on the web.

Instructor Bio
Dennis Helsel, PhD
Author of Nondetects And Data Analysis: Statistics for Censored Environmental Data

Dennis Helsel, PhD has 32 years experience applying statistics to practical issues in environmental sciences. He is the owner and lead scientist of Practical Stats, an environmental statistics training and consulting firm. He is the lead author of two textbooks, Statistical Methods in Water Resources (USGS, 2002), and Nondetects And Data Analysis: Statistics for Censored Environmental Data (Wiley, 2005), as well chapters in two handbooks and over 50 journal articles.

Dr. Helsel was a 2003 recipient of the Distinguished Achievement Award from the American Statistical Association's section on Statistics and the Environment, and of the Dept. of Interior's Distinguished Service Award in 2007. He has been invited to conduct training classes on environmental statistics to the Chinese Ministry of Water Resources; to the Umweltbundesamt (German Environment Agency); to students at the Helsinki University of Technology, Finland; and in the United States through the American Statistical Association.

Fee: 299.00 USD Per Webinar

Downloads: Session Slides (PDF)
Record of Attendance Form (PDF)

Number of Participants: Unlimited from a single computer (Broadcast webinar in your conference room or auditorium for no extra charge)

Continuing Education Certificates: Unlimited. $14.95 each. Official CEU certificates are available as an option and only available at the time of webinar participation from Northern Illinois University. Ordering steps are given at time of webinar order.

Access: On-demand, anytime 24/7.
Access Duration: 24 hours.

Discounts: Buy 3 on-demand webinars, and get 3 on-demand webinars for free!

Duration: 90 minutes
PDH Earned: 1.5 hours
Instructor(s): Dennis Helsel, PhD
Author of Nondetects And Data Analysis: Statistics for Censored Environmental Data

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