It is becoming more and more difficult to add new reserves to replace annual production from depleting oil and gas resources. Mos tof the "easy" oil and gas fields have been discovered, and now we must look for the more elusive accumulations and become more creative in devising improved or new production practices. Although advances in 3D seismic, horizontal drilling, completion techniques and computer application shave improved our ability to find and produce new reserves, risks have, unfortunately, increased. In addition to the technical risks, economic risks are becoming more burdensome. Various groups have attempted to develop standards to deal with this increasing uncertainty, but are encountering a great reluctance to change. The Petroleum Society Standing Committee on Reserves Definitions has been actively trying to promote a revised reserve classification system to serve as a standard for all reserves evaluations. The Society of Petroleum Engineers, the Society of Petroleum Evaluation Engineers, The World Petroleum Congress and the Canadian Securities Commissions are all looking at upgrading their respective Reserve Definitions. Every factor used in the evaluation of oil and gas assets has varying degrees of uncertainty associated wit it; thus, evaluators must have some knowledge of statistical methods in dealing wit the problem. There are many statistical techniques available to deal wit the problem of uncertainty, such as Monte Carlo Simulation, Expected Value and Decision Tree Analyses. These can be sophisticated or simple, depending upon the data, the resources, and the need to derive statistical measurements. The purpose of this paper is to emphasize the need to incorporate and standardize the application of risk, and to propose a revised Expected Value Method for the economic evaluations of reserves and dispel the myths that statistical procedures are difficult, time consuming, and expensive.