The Birnbaum-Saunders (BS) distribution as well as its respective regression models have been widely used in several fields, such as business, finance, insurance, management, and production (see the work of Leiva 1 ). There are at least three different modeling approaches in the BS context, which were introduced by Rieck and Nedelman, 2 Leiva et al, 3 and Balakrishnan and Zhu. 4 A common point in these regression models is that the presence of correlation is not considered, despite the fact that it is relatively common. Therefore, the objective in this discussion is to fill this gap with the introduction of a BS time series model that allows the inclusion of a regression structure. Moreover, this discussion brings a relatively little explored point in the context of BS models, which is the area of time series. Some recent studies on BS time series models are discussed in the works of Saulo et al 5 and Rahul et al. 6 The proposed model is specified in terms of a time-varying conditional mean and can be thought of as an extension of the reparameterized BS (RBS) regression model proposed by Leiva et al. 3 An example with simulated data is provided to illustrate the proposed methodology.
ORCIDHelton Saulo http://orcid.org/0000-0002-4467-8652 Jeremias Leão http://orcid.org/0000-0003-1176-0198 Manoel Santos-Neto