SROI is the most reliable tool for either developing a business case for funding for an initiative, or for evaluating the success of existing innovations, projects and services.
SROI is a special form of Benefits Management. It stands on the shoulders of evaluation frameworks that have gone before, so it recognises Cost/ Benefit analysis, and extends this to cover the cost/benefit of outcomes that may not have a direct financial benefit - it assigns a financial equivalent.
I've compared all of the different evaluation methods in the pages that follow - but read about SROI here!