The following pdf contains a set of lecture notes on credibility written by Ben Zehnwirth.
The study guide forms background material for a lecture on credibility given at the 1991 CAS Seminar on Ratemaking held on March 14-15 in Chicago, Illinois.
The notes have grown out of a number of sets of lecture notes prepared for statistical and actuarial courses at Macquarie University and the University of Copenhagen. They are intended to provide an introductory set of lectures on the subject of credibility and its intimate connections with linear regression, Bayes estimation, and recursive estimation.
Average link ratio methods can be formulated as regression estimators. A Buhlman-Straub credibility model is formulated for each link ratio regression model that facilitates the development credibility formulae for link ratios.
It is also shown that there are better formulae for adjusting link ratios than those based on Buhlmann- Straub.