Which metric is NOT typically used by EPRI in its research?

The correct choice is market share metrics, as this metric is typically associated with understanding a company's or product's position within a competitive landscape rather than the operational or technical aspects that EPRI focuses on in its research. EPRI primarily concentrates on quantitative measures that relate to the performance and reliability of electric power systems, including reliability metrics that assess how consistently and dependably electricity is delivered to consumers, environmental impact metrics that evaluate the ecological effects of power generation, and efficiency metrics that measure how effectively energy is converted and utilized. In contrast, market share does not provide direct insight into the operational standards or performance of electric utilities, making it less relevant to EPRI's focus on improving electric power systems and their sustainability.