Educational researchers commonly use the rule of thumb of "design effect smaller than 2" as the justification of not accounting for the multilevel or clustered structure in their data. The rule, however, has not yet been systematically studied in previous research. In the present study, we generated data from three different models…

A paradigm for experimental studies of conversation training is developed. This paradigm offers a way of interpreting conservation training studies as well as suggesting several fertile areas for future studies. (Editor)