Our Credentials


Dr. Dennis Helsel (PhD, Environmental Science and Engineering, Virginia Tech) has 40 years of 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 or sole author of two textbooks, Statistical Methods in Water Resources (USGS, 2002), and Statistics for Censored Environmental Data using Minitab and R, 2nd ed. (Wiley, 2012), as well chapters in two handbooks and over 50 journal articles.

Full list of publications (pdf)

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. Dr. Helsel is our primary instructor.

Practical Stats also subcontracts with other instructors who hold PhD's in Statistics or Mathematical Statistics, who have extensive experience in environmental statistics, quality control processes, load (mass transport in streams) estimation, statistical methods for groundwater contamination, and have set up technical training programs. Together, we have conducted training courses in the US and overseas since 1990. More information is available upon request.


Who Else Has Taken Our Courses?

".An excellent class overall which I will recommend to others"..."I really appreciated your explanations of some common concepts that were previously explained to me in 'foggier' ways"....."I enjoyed the class. Thank you!"......"I learned a lot. This course was very informative and a great refresher." -- students in our October 2001 AES course

The list of agencies and organizations sending students to our classes is too long to list. Below is just a sampling of some, over the years. Several agencies have had us back multiple times, a testimony to the value they have gotten from our work.

International Training
Health Canada
Environment Canada
Singapore Ministry of Water and Environment
Umweltbundesamt (German Environment Agency)
Helsinki University of Technology, Finland
University of Stockholm
Chinese Ministry of Water Resources

State and Regional Agencies
St. Johns River Water Management District (FL)
Minnesota Water Pollution Control Agency
Minnesota Dept. of Agriculture
California Dept. of Water Resources
CA Dept. of Pesticide Regulation
Santa Clara Valley Water District (CA)
San Diego Regional Water Quality Control Board
Portland Water Bureau
Kansas Dept. of Health and Environment
Colorado Dept. of Public Health and Environment
Arizona Dept. of Environmental Quality
Texas Commission on Environmental Quality
Washington State Dept. of Ecology
Montana Dept. of Environmental Quality
New Jersey Dept. of Environmental Protection
Florida Dept. of Environmental Protection

Federal and Tribal Agencies
Centers for Disease Control and Prevention (CDC)
National Park Service
US Army Corps of Engineers
US Bureau of Reclamation
US Environmental Protection Agency, Region 4
US Fish and Wildlife Service
US Geological Survey
US Nuclear Regulatory Commission
Penobscot Nation
Shoshone Bannock Tribes
Sac and Fox Nation
Pawnee Nation
Eastern Shawnee Tribe
Yurok Tribe

Companies, Corporations, Organizations
Herrera Environmental
Iowa Soybean Association
Groundwater Resources Assoc. of California
Contaminated Sites Approved Professionals Society
Society for Environmental Toxicology and Chemistry (North Calif)
Society for Environmental Toxicology and Chemistry (Rocky Mountain)
Keystone Environmental
GEI Consultants
URS Corporation
National Council for Air and Stream Improvement (NCASI)
Exxon Mobil
Tetra Tech

Local Government Agencies
New York City Dept. of Environmental Protection
City of Austin
City of Portland
City of Tulsa
City of Redmond, WA
Boise (ID) Environmental
Orange County, CA
Olmsted County, MN
King County, WA

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