Measuring Rate Change

Abstract
Motivation: Calculated rate changes can substantially affect loss ratio forecasts and thus are critical parameters for ratemaking. However, current methods are not well suited to a changing book of business.

Method: The analysis first explores the conceptual underpinnings of rate change and then applies the conclusions of this analysis to several practical problems.

Results: The proposed approach shows improved accuracy as compared to other methods, with particular significance for a nonstatic book of business.

Conclusions: I conclude that “rate change” measures the change in premium relative to loss potential. One can then apply this conceptual formulation in order to solve several problems that one confronts in practice: how to adjust for shifts in limits and deductibles, how to blend together changes in exposures when the portfolio uses several different exposure bases, and how to properly weight together granular measures of rate change (e.g., for each policy, subline, etc.) into an overall rate change for the entire portfolio.

Availability: Please contact the author at neil.bodoff@willis.com or neil_bodoff@yahoo.com

Keywords: Rate change, rate change factors, on-level adjustments, adjusted premium, exposure bases.

Volume
Winter
Page
1-22
Year
2009
Categories
Actuarial Applications and Methodologies
Ratemaking
Exposure Bases
On-level Adjustments
Actuarial Applications and Methodologies
Ratemaking
Experience Rating
Publications
Casualty Actuarial Society E-Forum
Authors
Neil M. Bodoff