This article featured in the Fall 2012 edition of the Stanford Social Innovation Review. It discusses how Root Capital and Acumen Fund propose a system for program evaluation that is akin to GPS.
"Measuring social impact is a quixotic pursuit. We both should know. Over the last several years, each of us has worked at leading social investment funds—Root Capital and Acumen Fund—measuring, managing, and communicating the social impact of our respective organizations’ investment portfolios. We have done a reasonable job counting outputs and aligning our performance with our own and other impact funds through the adoption of the Impact Reporting and Investment Standards (IRIS). But..."