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Generalized p-values and confidence intervals: a novel approach for analyzing lognormally distributed exposure data.

Authors
Krishnamoorthy-K; Mathew-T; Ramachandran-G
Source
J Occup Environ Hyg 2006 Nov; 3(11):642-650
NIOSHTIC No.
20037385
Abstract
The problem of assessing occupational exposure using the mean of a lognormal distribution is addressed. The novel concepts of generalized p-values and generalized confidence intervals are applied for testing hypotheses and computing confidence intervals for a lognormal mean. The proposed methods perform well, they are applicable to small sample sizes, and they are easy to implement. Power studies and sample size calculation are also discussed. Computational details and a source for the computer program are given. The procedures are also extended to compare two lognormal means and to make inference about a lognormal variance. In fact, our approach based on generalized p-values and generalized confidence intervals is easily adapted to deal with any parametric function involving one or two lognormal distributions. Several examples involving industrial exposure data are used to illustrate the methods. An added advantage of the generalized variables approach is the ease of computation and implementation. In fact, the procedures can be easily coded in a programming language for implementation. Furthermore, extensive numerical computations by the authors show that the results based on the generalized p-value approach are essentially equivalent to those based on the Land's method. We want to draw the attention of the industrial hygiene community to this accurate and unified methodology to deal with any parameter associated with the lognormal distribution.
Keywords
Analytical-methods; Analytical-models; Analytical-processes; Exposure-assessment; Mathematical-models; Standards; Statistical-analysis; Author Keywords: confidence interval; hypothesis test; Type 1 error
Contact
K. Krishnamoorthy, Department of Mathematics, 217 Maxim D. Doucet Hall, P.O. Box 41010, University of Louisiana at Lafayette, Lafayette, LA 70504
CODEN
JOEHA2
Publication Date
20061101
Document Type
Journal Article
Email Address
krishna@louisiana.edu
Funding Type
Grant
Fiscal Year
2007
NTIS Accession No.
NTIS Price
Identifying No.
Grant-Number-T42-OH-008434; Grant-Number-R01-OH-003628
Issue of Publication
11
ISSN
1545-9624
Source Name
Journal of Occupational and Environmental Hygiene
State
MN; LA; MD
Performing Organization
University of Minnesota Twin Cities
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