| Abstract: | GRITS/STAT 4.2 (Groundwater Information Tracking System with statistical analysis capability) enjoys widespread use in the groundwater community. GRITS/STAT is a free PC-based database system capable of performing many of the statistical methods promulgated by the EPA guidance documents: Statistical Analysis of Ground-Water Monitoring Data at RCRA Facilities, 1989, and Addendum to Interim Final Guidance, 1992. GRITS/STAT 4.2, however, suffered from numerous software problems and lagged behind current guidance, particularly in the implementation of statistical intervals. With the release of GRITS/STAT 5.0, many of the software problems that plagued GRITS/STAT 4.2 were addressed and an entirely new Statistical Intervals module was added to bring the software closer to current guidance. The GRITS/STAT 5.0 Beta Test produced a helpful list of work arounds to commonly reported problems. A comparison of the Parametric Confidence Interval methods in GRITS/STAT 4.2 and GRITS/STAT 5.0 illustrates the expanded utility offered by the new Statistics module. The Parametric Confidence Interval in GRITS/STAT 4.2 is only moderately useful for comparing individual wells to an alternate concentration limit (ACL) computed on average background samples. GRITS/STAT 5.0, however, offers users the ability to compare individual and pooled wells to ACLs computed on background averages and risk-based maximum concentration limits (MCLs). |
