Welcome to Practical Stats

Statistical training and consulting for the environmental sciences and natural resources. From Singapore to South Dakota, our courses have enabled scientists to build better regression models, test for trends, see multivariate patterns, and correctly interpret nondetect (censored) data.

Our Mission
To train scientists in air, water, soil, and biological sciences to make sense of your data.

Training Courses
Registration for our online on-demand courses in Environmental Statistics at our Online Training Center have closed. We will not be opening the courses up again. For the content of our Applied Environmental Statistics course, see the textbook Statistical Methods in Water Resources, below.

What's New?
The NADA2 package for R is now freely available at https://cran.r-project.org/package=NADA2 .

NADA2 goes well beyond estimating summary statistics in providing methods for data analysis of data with one or multiple detection limits. Without substituting any fraction of the detection limit(s), using NADA2 you can:
* Compute confidence, prediction and tolerance intervals
* Test for exceedances of a standard
* Perform matched pair (before/after, upstream/downstream, etc.) tests
* Test for group differences -- parametric, nonparametric and permutation tests
* Compute correlation coefficients and regression
* Draw QQ and partial plots to guide whether to transform x and y variables in regression
* Build multiple regression models and find models with the least error
* Perform parametric and nonparametric trend analyses
* Cluster groups of censored multivariate data
* Draw NMDS plots of censored multivariate data
* Test for group differences and trends of censored multivariate data
… .. and much more.

Free Texbook - Statistical Methods in Water Resources
The 2020 version of the classic textbook Statistical Methods in Water Resources is now available as
1. a free download. See the link on our Books page
2. an inexpensive hardcopy sold by the US Geological Survey, at https://store.usgs.gov/product/533012


We've provided statistical training for the environmental sciences and natural resources since 1990 in the United States, Europe, Asia and the Middle East. See our credentials page and Dennis Helsel's publications list on ResearchGate. We clearly communicate information to the working scientist. We make statistics current, accurate, and practical.

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