ORTHOGONAL REPARAMETRIZATION IN ACCELERATED LIFE TESTS WITH THE POWER MODEL

Francisco LOUZADA NETO[1]

Josemar RODRIGUES[2]

§    ABSTRACT: Accelerated life tests are commonly used in industries of various areas in the estimation of the mean life time manufactured components. In this paper we are considering the power model with an exponential distribution for the life times. Assuming type II censored data, we study the effect of the orthogonal reparametrization ( Cox & Reid, 1987) in the inference of the mean life time under the usual level of a stress variable in an accelerated life test. We show that the profile likelihood function for this parameter is invariant under this type of reparametrization. Also, a numerical example is provided.

§    KEYWORDS: Accelerated life tests; power model; profile likelihood function; orthogonal reparametrization.

 



[1] DESs-UFSCar – CP 676 - 13565-905 - São Carlos - SP.

[2] ICMSC-USP – CP 668 - 13560-970 - São Carlos - SP.