This is something that big donors and big NGOs spend a huge amount of time talking about. If they've come up with something good, it didn't happen while I was w

This is something that big donors and big NGOs spend a huge amount of time talking about. If they've come up with something good, it didn't happen while I was working in the space. A single global metric is almost impossible. For one thing, it requires a horde of comparative value judgements. What is the exact impact difference percentage between feeding a child in Mali for a month, vs teaching a Kenyan man how to start a bicycle repair business? How organizations evaluated in the real world? Most funding comes from two kinds of donors - lets call them whales and consumers. Consumers get advertised to and give < $1,000 a year. Whales however usually have dedicated contacts an organization, and if they are giving enough, probably have access to both per project financials and project outcome metrics. So in theory whales have good information about the effectiveness of their money. Consumers though mostly don't. Partly consumers themselves are to blame for this because in general they don't care about how effective their giving is. The William and Flora Hewit foundation gave up on funding charities rating programs because of a study that found that less than 2% of donors ever research the effectiveness of the organizations they give to. Personally, I only give to organizations I've worked with.