Many development projects lack data to support their implementation. This does not mean that the projects are not having a positive impact. It could simply be that the data is harder to collect than the project is to implement. After all, for us to know how much water our windmill is pumping we would have to sit and watch it 24/7. It's just not feasible. Or it wasn't until now.
1. How much water the windmill pumped
2. Its average speed/output during the times when it was moving
3. The "up time" or proportion of time it was actually moving
Our goal is to maximize the amount of water pumped. When we make modifications to the windmill, we observe changes in the average output and up time. For example, if we decrease the pump displacement, we would expect to see average speed and "up time" increase because there is less resistance. We can now see if these increases are enough to overcome the loss of displacement to pump more water overall.