Bill Gates argues in his letter that measurement is the key to improving human condition.

I have been struck again and again by how important measurement is to improving the human condition. You can achieve amazing progress if you set a clear goal and find a measure that will drive progress toward that goal-in a feedback loop similar to the one Rosen describes. This may seem pretty basic, but it is amazing to me how often it is not done and how hard it is to get right.

What to measure ?

Given a goal, you decide on what key variable you need to change to achieve it-the same way a business picks objectives for inside the company like customer satisfaction-and develop a plan for change and a way of measuring the change. You use the measurement as feedback to make adjustments. I think a lot of efforts fail because they don't focus on the right measure or they don't invest enough in doing it accurately.

Also buried in the long letter

Ethiopia found a successful model for achieving this goal in the Indian state of Kerala, which had lowered its child mortality rate and improved a host of other health indicators, in part through a vast network of community health care posts. 

The data oriented way to approach to solve  lot of problems is like a CEO and they can back it up with success stories.