Upper Confidence Limit (UCL) Comparisons
Upper Confidence Limit (UCL) Comparisons
See Also:
Confidence limit comparison methods implemented in ChemStat fall into two categories:
1. Confidence limits calculated from compliance point sample concentrations and compared to a predefined comparison level such as MCL or action limit. These techniques are described in USEPA 1989 and 1992 statistical analysis guidance documents and the USPEA 1992 statistical training course.
Methods following this implementation include:
2. Compliance point sample concentrations compared to confidence limits calculated from background data. These techniques are described in the USEPA December 2002 guidance document "Calculating Upper Confidence Limits for Exposure Point Concentrations at Hazardous Waste Sites." These methods are commonly applied to CERCLA regulated sites.
Methods following this implementation include:
- Student's t-test Parametric Confidence Interval
- Land's Formula Confidence Interval (calculated from background)
- Bootstrap Resampling UCL Method
- Jackknife Procedure UCL Method
- Central Limit Theorem
- Chebyshev Non-Parametric Inequality Method
UCL Individual Well Calculations
The following methods can be used to calculate UCL for individual wells (compliance/background/unused) for all samples from that well for a parameter.