Student's t-test UCL Method

 (Background to Compliance Comparison)


See Also:

Upper Confidence Limit (UCL) Comparisons

 

Description:

 

The Student's t-test UCL Method is provided in the USEPA statistical guidance document "Calculating Upper Confidence Limits for Exposure Point Concentrations at Hazardous Waste Sites." The method is a parametric test for calculation upper confidence limits from measured sample concentrations.

 

 

Use:

 

Use the Student's t-test UCL method to calculate a 95% upper confidence limit from a collection of sample of environmental media collected at the site. The UCL is only calculated from sampling points listed as background. Compliance samples are not required, but if compliance samples do exists, each compliance sample concentration will be compared to the UCL. A statistically significant increase is indicated if the compliance sample concentration exceeds the UCL.

 

 

Remarks:

 

The method is designed for CERCLA compliant sampling programs. Unlike RCRA sampling which typically monitors the same sampling points for an extended period of time, this method is suitable for collections of samples taken at one point in time, but from many locations at the regulated site.