“…For each case of missing data, authors were contacted no more than twice. Of the 44 requests for data made, 17 responses (38.6%) provided the requested data [1,3,5,7,11,27,28,31,34,42,53,66,69,70,80,83,84] . Thirteen responses (29.5%) indicated that the data was no longer available [10,12,37,46,49,51,57,58,64,67,71,75,76] , the authors of 14 studies could not be contacted or did not reply to the request for data [6,16,19,26,47,48,50,52,72,77,82,85,86] , and authors of two eligible studies were not contacted, as they did not measure any of the extracted outcomes [24] or the sample included only girls and could not be included in the meta-analysis of sex differences [41] .…”