Premium
Estimation, reference ranges and goodness of fit for the three‐parameter log‐normal distribution
Author(s) -
Royston Patrick
Publication year - 1992
Publication title -
statistics in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.996
H-Index - 183
eISSN - 1097-0258
pISSN - 0277-6715
DOI - 10.1002/sim.4780110707
Subject(s) - goodness of fit , normality , statistics , normal distribution , confidence interval , mathematics , estimation theory , computer science
The three‐parameter log‐normal distribution (3PL) is an appropriate model for many of the continuous variables encountered in medicine. It is shown how to obtain different types of estimate and approximate (sometimes conservative) confidence intervals for the parameters of the 3PL and for certain functions of them, particularly in the calculation of reference ranges of clinical measurements. A simple non‐iterative estimate of the shift parameter is described. The Shapiro–Wilk test of non‐normality is modified to allow it to be used for testing for departure from the 3PL. Its power is compared with that of other well‐known tests. The methods are illustrated using several data sets.