| LLw {WeibullR} | R Documentation |
Log Likelihood for weibull fitted data, failures and suspensions only
Description
Determination of log-likelihood values for the basic distributions covered by R should be ubiquitous, but an implementation is provided here to enable likelihood ratio testing particularly for comparison of 3-parameter optimized models with their 2-parameter counterpart.
Usage
LLw(x, s=NULL, Eta, Beta)
Arguments
x |
A vector of failure data. |
s |
An optional vector of suspension data. |
Eta |
The scale parameter from a weibull fit. |
Beta |
The shape parameter from a weibull fit. |
Details
Function LLw can only handle datasets with failure and suspension data. For data including intervals wblrLikelihood can be used.
This function is somewhat unique among likelihood functions in that it will scan the suspension data for
removal of negative values. Such negative values are likely to be entered as data is provided
for a 3-parameter fit by explicitly providing the original data with vector subtraction by the optimized t0.
The primary intention for likelihood determination is to permit likelihood ratio testing for comparison
of 3-parameter optimized models with their 2-parameter counterpart.
Value
Returns a log-likelihood value.
References
Robert B. Abernethy, (2008) "The New Weibull Handbook, Fifth Edition"
Marie Laure Delignette-Muller, Christophe Dutang (2015). "fitdistrplus: An R Package for Fitting Distributions". Journal of Statistical Software, 64(4), 1-34. URL http://www.jstatsoft.org/v64/i04/.
Examples
failures<-c(90,96,30,49,82)
suspensions<-c(100,45,10)
fit<-lslr(getPPP(failures, suspensions))
LL<-LLw(failures, suspensions, fit[1], fit[2])