The website Retraction Watch has an interesting interview with MICHAEL FINDLEY about an experiment undertaken at Comparative Political Studies last year. The journal sponsored a special issue for which they solicited submissions where results were not reported.  Submissions were of two types: (i) planned research in which the results were not yet realized, and (2) completed research in which the results were removed from the paper.  The purpose of the experiment was to see if they could learn anything about publication bias.  The “sample size” was small.  Nineteen submissions, and only three papers accepted under these conditions, two of which had “null results” to some extent.  The interview can be read here.  And a link to the paper discussing the lessons learned from the experiment is here.