A comparison of upper confidence limits for skewed distributions

Remediation decisions at contaminated sites are determined by comparing the Upper Confidence Limit (UCL) of the mean contaminant to a site-specific action level. The Environmental Protection Agency (EPA) has established methods for computing this UCL, also called the Exposure Point Concentration (EPC) term; The UCL formula depends upon the distribution of the contaminant concentrations, which are often positively skewed. The EPA frequently recommends the Lognormal distribution to model such data. However, that assumption often causes the UCL to be unreliable. What is the role of skewness in computing UCL statistics over different distributions? Computer simulation is used to test a range of skewness values over three similarly shaped distributions: Lognormal, Gamma, and Weibull. Three statistical tests will also be evaluated: Student's t-Statistic, Chebychev's Inequality, and Land's H-Statistic to compute the UCL. By modeling skewness effectively, we can determine the most appropriate distribution and statistical method to use in computing UCLs.

Name thesis:degree_name

Master of Science (MS)

Level thesis:degree_level

Thesis

Discipline thesis:degree_discipline

Mathematics

Grantor dc:publisher

University of Nevada, Las Vegas

Year

2002

Author dc:creator

• Theemling, Michael Gary

Contributors dc:contributor

• Ashok Singh

Statement dc:rights

• IN COPYRIGHT. For more information about this rights statement, please visit http://rightsstatements.org/vocab/InC/1.0/

Language dc:language

English

Identifier

https://oasis.library.unlv.edu/rtds/1446

OAI identifier oai:identifier

oai:oasis.library.unlv.edu:rtds-2445