Number of studies that use an appropriate statistical method.

†Numbers of studies in phase 2 that were assessed independently by two assessors and used a statistical method; numbers in each row sum to twice the number of studies. *Of the 48 studies assessed in more detail, and that used and described a statistical method, 87% (34/39) were judged to have used a correct statistical method, and in 12% (5/39) of the papers assessed there was insufficient information reported in the publication to be able to make this judgement.