In public good games, voluntary contributions tend to start off high and decline as the game is repeated. If high contributors are matched, however, contributions tend to stay high. We propose a formalization predicting that high contributors will self-select into groups committed to charitable...

We present preliminary results from a small-scale natural field experiment aimed at exploring online social contagion, with an application to charitable giving. We worked in partnership with Heifer International, a non-profit organization aimed at fighting poverty in developing countries, and...