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...

When asking for donations, charitable organizations often use suggestions concerning the amount of potential contributions. In our randomized field experiment, opera visitors received solicitation letters asking to support a social youth project organized by the opera house. The three different...