Social Preferences? Google Answers!

We analyse pricing, e¤ort and tipping decisions in the online service GoogleAnswers. While users set a price for the answer to their question ex ante, theycan additionally give a tip to the researcher ex post.In line with the related experimental literature we …nd evidence that tippingis motivated by reciprocity, but also by reputation concerns among frequentusers. Moreover, researchers seem to adjust their e¤ort based on the user’sprevious tipping behaviour. An e¢ cient sorting takes place when enough tiphistory is available. Users known for tipping in the past receive higher e¤ortanswers, while users with an established reputation for non-tipping tend to getlow e¤ort answers.In addition, we analyse how tipping is adopted when the behavioural defaultis not to tip and estimate minimum levels for the fraction of genuine reciprocatorand imitator types.