In insurance practice, one of the crucial tasks of actuaries is to determine adequate premiums to be charged for risks and there have been a variety of in-surance pricing methodologies to serve this purpose. Credibility ratemaking is a technique for predicting future claims of a risk class, given past claims of that and related risk classes. Mowbray (1914) provided an early introduction to practical aspects of this technique. Buhlmann (1967) derived a credibil-ity formula which has the form of weighted sum ...