Further considerations of modified moment estimators for weibull and lognormal parameters

Abstract

A modification of moment estimators of the three-parameter Weibull and lognormal distributions are presented. The equation involving the third moment is replaced by F(x₁ )= l/(n+l), where x₁ is the sample value of the first order statistic and n is the sample size.These estimators often are easier to calculate than previously presented Cohen, Whitten, Ding (CWD) estimators in which the third equation is E(X₁) = x₁ for the Weibull distribution and E[£n(X₁ - τ)] = n(x₁ - τ) for the lognormal distribution.Calculations are made easy with the aid of accompanying tables and charts. Three illustrative examples are included

Keywords:

• Weibull Distributions
• Lognormal Distributions
• skewed distributions
• life-testing distributions
• modified moment estimators