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Statistical Software ProUCL 5.2 for Environmental Applications for Data Sets with and without Nondetect Observations

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ProUCL Fact Sheet

ProUCL version 5.2.00 (5.2) is the latest update of the USEPA ProUCL statistical software package for analysis of environmental data sets with and without nondetect (ND) observations. ProUCL version 5.2 is a comprehensive statistical software package with statistical methods and graphical tools to address many environmental sampling and statistical issues. Version 5.2 is the latest version of the software that has been updated to include improvements to the Technical Guide and the User Guide for clarity, code updates to correct for reported bugs, and several changes made to the decision logic for the recommendation of UCLs for this version. The Technical Guide and Users Guide due to size are now downloaded separately from the program.

Historically, ProUCL has placed emphasis on achieving adequate coverage, but not on achieving an accurate estimate of the mean, in the sense of an upper bound for the mean that is as close as possible to the true mean while maintaining the desired coverage. Depending on the data, there are some UCL estimators in ProUCL (particularly Chebyshev and H) that can generate gross overestimates of the mean so that adequate coverage will almost certainly be achieved in these cases, but accuracy suffers. Although this philosophy ensures that the likelihood of one decision error will be small (i.e., Type I error, concluding a site is not contaminated when it is), such an overestimate can result in a high likelihood of the opposite decision error (i.e., Type II error, concluding a site is contaminated when it is not). The objective should be to not only control for Type I error, but also to protect against large Type II errors. This requires balancing both objectives (coverage and accuracy) to select the most appropriate UCL method. 

Citation: USEPA.  ProUCL: Statistical Software for Environmental Applications for Data Sets with and without Nondetect Observations. Version 5.2. https://www.epa.gov/land-research/proucl-software,  2022. 

Updated Operating Systems

ProUCL 5.2 is compatible with Microsoft Office 10.0 and 11, and represents an upgrade of all previous versions of ProUCL. ProUCL 5.2 has been developed in Microsoft .NET Framework 4.7.2 using the C# programming language. To provide Excel-compatible Spreadsheet functionality, ProUCL uses GrapeCity Spread.NET 14; and the development software package, ChartFX 8 for graphics. With the exception of slight differences in graphical display, the look of ProUCL 5.2 is very similar to version 5.1. Any differences are addressed in the User Guide. 

Code updates and corrections of reported software bugs: 

  • Added a space in between the ProUCL version number and date in the output.
  • Improved warning display about when the data pass only one of the two GOF tests to be more readable. 
  • Never recommend gamma or bootstrap UCLs when the sample size is less than 10.
  • Made the random seed constant so that bootstrap UCLs are reproducible. 
  • Standardized names for gamma UCLs. 
  • Added a flag for when the KM method may be inappropriate, which is set when any of the KM UCLs are less than the mean computed using half the DL. This can happen when there is an order-of-magnitude difference in DLs. 
  • Fixed UCL output in which the KM (t) UCL displayed a different value that the KM Student’s t-UCL. 
  • Monte Carlo Simulation Module that hasn’t been completely developed was removed. 
  • Removed the Jackknife UCL since it is numerically equivalent to the t-UCL. 
  • Fixed outlier test for n >500 such that the output informs the user the test is not available for large sample sizes, rather than displaying an incorrect result. 
  • Fixed nonparametric UTL output that recommended incorrect order statistics for various sample sizes. 
  • Fixed bug in which it was necessary to close Excel files before reopening them in 5.1. 
  • Fixed graphics bug that resulted in an error message for Unhandled exceptions. 
  • Fixed lognormality GOF test in the UCL with NDs modules for gamma, normal, and non-parametric only.  

Enhancements to UCL Recommendations

Changes to UCL recommendations were made based on three simulation studies performed by Neptune and Company, Inc (see Appendix D of the Technical Guide) with an aim to better align ProUCL with the DQO process, under which accuracy must be an important consideration. In ProUCL 5.2, the decision logic for goodness-of-fit has been modified so that more robust UCL estimators are selected more often. The Chebyshev UCL is no longer recommended, and the H UCL is only recommended in cases of moderate to large sample sizes when there is high confidence that the assumption of lognormality is met to a good approximation. It has been noted that in some cases, data may be too skewed or not numerous enough to determine an appropriate UCL. ProUCL 5.2 does not provide a recommendation in these cases but encourages the user to: 1) verify that the data were collected randomly (rather than through biased sampling, such as hot spot delineation sampling or best professional judgment sampling); 2) consider site knowledge that may explain why the data may be skewed (such as small areas of high concentrations); and 3) to contact a statistician if ProUCL cannot provide a recommendation. A detailed description of the justification for these changes is in Technical Guide Section 2.5, and new decision logic charts are available in Appendix A of the same guide. 

User and Technical Guide Updates

Both guides have been updated to include all recent changes to the program and to be more user friendly and informative and are now downloaded separately from the program for ease of reference and use.  

References

Interstate Technology Regulatory Council (ITRC). 2012. Incremental Sampling Methodology. Technical and Regulatory Guidance, 2012.

U.S. Environmental Protection Agency (EPA). 1989a. Methods for Evaluating the Attainment of Cleanup Standards, Vol. 1, Soils and Solid Media. Publication EPA/230/2-89/042.

U.S. Environmental Protection Agency (EPA). 1992. Statistical Analysis of Ground-water Monitoring Data at RCRA Facilities. Addendum to Interim Final Guidance. Washington DC: Office of Solid Waste. July 1992.

U.S. Environmental Protection Agency (EPA). 1994. Statistical Methods for Evaluating the Attainment of Cleanup Standards, EPA 230-R-94-004, Washington, DC.

U.S. Environmental Protection Agency (EPA). 2000. U.S.

Singh, A.K., Singh, A., and Engelhardt, M. 1997. The Lognormal Distribution in Environmental Applications. Technology Support Center Issue Paper, 182CMB97. EPA/600/R-97/006, December 1997.

Singh, A., Singh, A.K., and Iaci, R.J. 2002. Estimation of the Exposure Point Concentration Term Using a Gamma Distribution, EPA/600/R-02/084, October 2002.

Singh, A. and Nocerino, J.M. 2002. Robust Estimation of Mean and Variance Using Environmental Data Sets with Below Detection Limit Observations. Vol. 60, pp. 69-86.

Singh, A., Maichle, R., and Lee, S. 2006. On the Computation of a 95% Upper Confidence Limit of the Unknown Population Mean Based Upon Data Sets with Below Detection Limit Observations. EPA/600/R-06/022, March 2006.

Training for ProUCL

Five archived webinars are available for learning more about ProUCL. 

Contact Information for ProUCL

The ProUCL software is developed under the direction of the ORD Site Characterization and Monitoring Technical Support Center (SCMTSC). Any comments or questions concerning ProUCL should be addressed to: 

Felicia Barnett ([email protected])
Director, Site Characterization and Monitoring Technical Support Center 
USEPA/ORD/CESER/Region 4 
461 Forsyth Street, S.W.  
Atlanta, GA 30303-8960  

Installation Instructions

  1. Download the file ProUCLInstall.msi from the top of this page and save to a temporary location. Note: You can delete this file when the installation is complete.  

  1. Double click the ProUCLInstall.msi file and follow the installation instructions provided by the install wizard. 

  1. To run the program, click windows icon on the far-left side of the Task bar and navigate to ProUCL 5.2. Open the folder and click on ProUCL 5.2 to start the program.  

    1. To pin ProUCL to Taskbar, right click ProUCL icon displayed on Taskbar and click Pin to Taskbar.  

  2. To uninstall the program, open the Windows settings dialog then choose Apps. Search through the list of installed applications for ProUCL. Click on ProUCL and then click the Uninstall button.  

  3. To access Data folder, click windows icon on the far-left side of the Task bar and navigate to ProUCL 5.2. Open the folder and double click on Data. 

Minimum Hardware Requirements

  • Windows 10 or 11 compatible PC - ProUCL 5.2.00 will function but some titles and some Graphical User Interfaces (GUIs) will need to be scrolled. Definition without color will be marginal. 
  • Minimum graphics display of 800 by 600 pixels 
  • Basic Color is preferred

Software Requirements

ProUCL 5.2.00 has been developed in the Microsoft .NET Framework 4.0 using the C# programming language. To properly run ProUCL 5.2.00 software, the computer using the program must have the .NET Framework 4.0 pre-installed. The downloadable .NET Framework 4.0 files can be obtained from one of the following websites: 

Documentation Downloads

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Last updated on November 20, 2024