Comparison of Incurred But Not Reported [IBNR] Methods

Research Projects – Health


The Health Section is pleased to make available the results of a research project that assesses the accuracy of commonly used IBNR estimation methods over a wide range of scenarios. The report and accompanying model were prepared by Cabe Chadick, Wes Campbell, and Finn Knox-Seith of Lewis and Ellis.


Comparison of Incurred But Not Reported IBNR Methods

Incurred But Not Reported [IBNR] Model

Thank You

The Health Section would like to thank the members of the Project Oversight Group ("POG"), who provided advice and guidance during the course of the project.

The members of the POG were:

  • John Stenson, Chair
  • Michael Bears
  • John Governale
  • Peter Howard
  • Pat Kinney
  • David Nelson
  • Bernie Rabinowitz
  • Eric Smithback
  • Martin Staehlin
  • Steven Siegel, SOA Research Actuary
  • Barbara Scott, SOA Research Administrator

Questions Or Comments?

If you have comments or questions, please send an email to


The report, accompanying model, and other documentation contained herein do not represent an official position, statement, or endorsement on behalf of the Society of Actuaries or its members for a particular method or combination of methods for calculation of incurred but not reported reserves (IBNR), nor should the material be construed to do so. It is the product of a research effort commissioned by the Society of Actuaries Health Section to add to the library of resource information for the estimation of IBNR reserves and further knowledge in that area. The material is neither intended to preclude the use of other methodologies for estimation of IBNR reserves for any purpose nor provide an official statement or position on the use, application, or preferability of other methodologies as compared to the methodologies described herein.