Social Preferences? Google Answers! Volume 3 Jena Economic Research Papers 2009-05-11 2009 2007 2009-035 social preferences reciprocity moral hazard reputation Internet psychological game theory We analyse pricing, e¤ort and tipping decisions in the online service ‘Google Answers’ While users set a price for the answer to their question ex ante, they can additionally give a tip to the researcher ex post In line with the related experimental literature we …nd evidence that tipping is motivated by reciprocity, but also by reputation concerns among frequent users. Moreover, researchers seem to adjust their e¤ort based on the user’s previous tipping behaviour. An e¢ cient sorting takes place when enough tip history is available. Users known for tipping in the past receive higher e¤ort answers, while users with an established reputation for non-tipping tend to get low e¤ort answers. In addition, we analyse how tipping is adopted when the behavioural default is not to tip and estimate minimum levels for the fraction of genuine reciprocator and imitator types. jportal_jpjournal_00000016 2009-05-11T11:37:04.804Z 2010-12-17T11:54:00.890Z