K. Krishnamoorthy
University of Louisiana at Lafayette
Confidence Limits for Lognormal Percentiles and for Lognormal Mean based on Samples with Multiple Detection Limits
The problem of assessing occupational exposure using the
mean or an upper percentile of a lognormal distribution
is addressed. Inferential methods for constructing an upper
confidence limit for an upper percentile of a lognormal
distribution and for finding confidence intervals for a lognormal
mean based on samples with multiple detection limits are proposed.
The proposed methods are based on the maximum likelihood estimates. They
perform well with respect to coverage probabilities as well as power,
and are satisfactory for small samples. The proposed approaches are also
applicable for finding confidence limits for the percentiles of a gamma distribution.
An advantage of the proposed approach is the ease of computation and implementation.
An illustrative example with real data sets is given.