Webinars

National Water Quality Monitoring Council Webinar Series

"Nondetects and Data Analysis" 

Featuring a presentation by Dennis R. Helsel, PracticalStats.com

When: Tuesday, November 15, 2016 at 2:00 PM (ET)
Registration: Pre-registration is REQUIRED for this event.  To register, please click here and register.  Once your registration has been approved, you will receive a confirmation email with instructions for joining the Webinar.

If you miss the webinar and would like to view them later, please visit our YouTube page to view our archive of webinars, or, visit our website for more information

Abstract:  Measurements of trace chemicals in environmental media (water, air, soils, biota) frequently result in values reported only as less than the laboratory’s reporting limit (“less-thans”,  “nondetects”, and “qualified values”).  In statistical jargon these are "censored data".  This webinar will provide an overview of methods for analysis of censored data, from estimating summary statistics to regression and hypothesis tests, including methods that incorporate data censored at multiple limits.  Material is drawn from the textbook  Statistics for censored environmental data using Minitab and R  by Helsel, 2012.

What you will learn:

  • the consequences of substituting one-half the reporting limit on data analysis (spoiler alert: its not good),
  • what software is available for analysis of censored data,
  • what nonparametric methods are available for estimating summary statistics, test for differences between groups, and for correlation/regression of censored data
  • what parametric methods are available for estimating summary statistics, test for differences between groups, and for correlation/regression of censored data

Relevant materials will be provided online for you to digest at your leisure afterward.

 

NPDES Webinars (recorded)

 

The NPDES permit program, created in 1972 by the Clean Water Act (CWA), helps address water pollution by regulating point sources that discharge pollutants to waters of the United States. The permit provides two levels of control: technology-based limits and water quality-based limits (if technology-based limits are not sufficient to provide protection of the water body). The US Environmental Protection Agency provides a number of recorded webcasts that can help the stormwater professional in understanding the basics as well as the intricacies of the National Pollutant Discharge Elimination System.  The links below point to previously recorded webcasts relating to the following stormwater topics: