There is a general utilization of reliability models throughout the world as the advantages of probabilistic methods over the deterministic approaches to planning, designing, operating and maintaining the electric utility systems have clearly been recognized. Quantitative system reliability planning is essentially linked with equipment forced outage statistics computed from operating experience records. Therefore, generation and transmission equipment outage data have become an important component of power system planning, operations and maintenance practices. The collection of power system outage data is an integral part of an effective reliability assessment system that provides the tools and information necessary to assist utility engineers and management in the primary objective of supplying reliable electric service at the lowest possible cost. This paper presents some fundamental equipment outage data concepts for generation and transmission equipment with actual examples of the use of different statistical performance variables based on the Canadian Electricity equipment databases