Thanks for sharing. This is fascinating. David McKenzie in our research group has been looking at this and finds different results in Ghana. Perhaps if you could look at his work http://poverty-action.org/sites/default/files/McKenzie-Paper.pdf, and see whether your approach was different (and if so how), it would add enormously to this debate. The social reasons you mention above sound very important. I don't know either country well, so if you can elaborate, that would be great.