Evidential reasoning for WebTrust assurance services

In this paper we develop an evidential network model for "WebTrust Assurance", a service recently proposed by the American Institute of Certified Public Accountants and the Canadian Institute of Chartered Accountants. Our model augments the AICPA/CICA approach and presents five categories of assertions related to providing WebTrust Assurance. We then derive goals, sub-goals and evidence that are related to the overall assurance to be provided. The aggregation of evidence and the resolution of uncertainties in the model follow the approach of Dempster-Shafer theory of belief functions. Next we consider the assurance planning problem and develop a decision theoretic model for this problem.