rba {WeibullR}

Reduced Bias Adjustment for Weibull and Lognormal MLE

Description

rba This function generates reduction factors based on the median bias of the Weibull Beta parameter MLE (C4^3.5), alternatively based on the mean bias(C4^6), and a single factor for both median and mean of the symmetrical lognormal distribution.

Usage

 rba(Qx, dist="weibull", basis="median")

Arguments

Qx

The quantity of failures in data (right-censored data, or suspensions excluded)

dist

A string defining a distribution to be fit. Implemented distributions are "weibull" (default) and "lognormal".

basis

a string value indicating the basis for bias reduction, "median" is the default, but "mean" may be chosen.

Details

Many references discuss the bias reduction in terms of mean reduction. Abernethy has promoted consideration of the RBA in terms of median bias reduction.

Value

A factor to be multiplied to the MLE Beta or log-Sigma for bias reduction.

References

Robert B. Abernethy, (2008) "The New Weibull Handbook, Fifth Edition"

Examples

failures<-c(90,96,30,49,82)
suspensions<-c(100,45,10)
MLEfit<-mlefit(mleframe(failures,suspensions))
MLE_RBA<-c(MLEfit[1],MLEfit[2]*rba(length(failures)))