have been quite keen to publish negative findings (6 nagative reports have appeared in the last 3 years, all of which are taking part in the meta-analysis, although curiously most positive reports appearing over this time period have not been invited to take part). Culverhouse et al. allow unpublished studies to submit data for the meta-analysis, and they report that they have trawled for these unpublished studies. As such, requiring N > 300 to prevent the file drawer problem does not seem necessary.
