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Reconciling Two Rate Level Indications: A Chain Rule Approach, Cheng-Sheng Peter Wu

Journal of Actuarial Practice (1993-2006)

The problem considered is that of reconciling two rate level indications that are based on several common factors, but have been made at different review periods. A popular approach to this problem is the so-called sequential replacement method, which calculates the impact of each individual factor. Unfortunately, this method has a serious deficiency: the estimated impact of a factor depends upon the order of the replacement. To counteract this defect, a new approach, called the chain rule approach, is developed. Using this approach, an explicit formula is given for calculating the impact and the marginal impact of each factor.