A LOG LINEAR-MODEL FOR THE BIRNBAUM-SAUNDERS DISTRIBUTION

The Birnbaum-Saunders distribution was derived to model times to failure for metals subject to fatigue. In this article, we formulate and develop a log-linear model for the Birnbaum-Saunders distribution. The model may be used for accelerated life testing or to compare the median lives of several populations. Methods of analyzing data for this log-linear model are discussed, with maximum likelihood and least squares methods being compared. It is found that, for commonly occurring conditions, the notorious intractability of the Birnbaum-Saunders distribution is not a serious problem because least squares and normal-theory procedures provide a reasonable alternative.