[modifiedweibull_ex0] Modified Weibull Model

   [modifiedweibull_ex1]
   

   model
   {
      for( i in 1 : N )
      {
      x[i] ~ dweib.modified(alpha, beta, lambda)
         hrf[i] <- hrf(x[i], x[i])
         reliability[i] <- R(x[i], x[i])   
      }
      
   # Prior distributions of the model parameters   
   
         alpha ~ dunif(0.001, 1.0)
         beta ~ dunif(0.001, 1.0)
         lambda~ dunif(0.001, 1.0)      
   }

The data set is taken from Aarset(1987).

Lai, C.D. , Xie, M. and Murthy, D.N.P. (2003). A modified Weibull distribution,
IEEE Trans. Reliab ., 52, 33–37.

Ng, H.K.T.(2005). Parameter estimation for a modified Weibull distribution, for progressively type-II censored samples,
IEEE Trans. Reliab ., 54, 374–380.

Aarset, M.V.(1987). How to identify bathtub hazard rate.
IEEE Trans Reliab ., 36(1), 106 –108.

The MLE’s ( Lai et al., 2003) are  
alpha = 0.0876    beta = 0.389;   lambda = 0 .01512

The linear regression estimates (Ng, 2005) are  
alpha = 0.0624    beta = 0.355;   lambda = 0 .02332

Data ( click to open )

Inits for chain 1        Inits for chain 2     ( click to open )

Results

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