International development expert Professor Robert Lensink set out to examine a widely-held concept in aid. He found there was little evidence to support it.

"Many NGOs have the idea that that information travels freely between people," Lensink explains. "We tested if it was true that if one person was trained, after a year another person in their group would learn from them. We found that the training worked, but no evidence of a spillover effect. This idea that NGOs have, that information travels freely between people, doesn’t hold."