Science publishers are sending out decidedly mixed messages about how seriously they take the impact factor — the much-maligned measure of how often the average research paper in a journal is cited.

A record number of journals — 66 of them, including 33 37* new offenders — have been banned from this year’s impact-factor list (released today) because of excessive self-citation or because of ‘citation stacking’ (in which journals cite each other to excessive amounts). This year, the named-and-shamed titles include theInternational Journal of Crashworthiness and the Iranian Journal of Fuzzy Systems. Only 51 were banned last year (28 new offenders), and 34 the year before that. Along with the record numbers, Thomson Reuters has posted a new explanation of why it decides to ban journals — essentially because the self-citations distort the rankings. *Thomson Reuters updated the number of new offenders from 33, to 37, on 20 June.