The Internet experiment is now a well-established and widely used method. The present paper describes guidelines for the proper conduct of Internet experiments, e.g. handling of dropout, unobtrusive naming of materials, and pre-testing. Several methods are presented that further increase the quality of Internet experiments and help to avoid frequent errors.

These methods include the “seriousness check”, “warm-up,” “high hurdle,” and “multiple site entry” techniques, control of multiple submissions, and control of motivational confounding. Finally, metadata from sites like WEXTOR (http://wextor.org) and the web experiment list (http://genpsylab-wexlist.uzh.ch/) are reported that show the current state of Internet-based research in terms of the distribution of fields, topics, and research designs used.