investigating the effect of systematic errors in the isi subject categories on the scientific outputs and the visibility of disciplines

purpose: the purpose of this study was to investigate the structure of the discipline categorization and its overlap with isi subject categories. this will help detect the systematic errors arising from the scientometrics studies. methodology: the scientometrics methodology was used. all articles which were indexed in the web of science database (2007) and also the articles citing them during 2007-2011 were retrieved and categorized. findings: the findings show that the articles in the social science citation index had the highest overlap (32420) with the science citation index expanded (32.79%) and the articles in the art & humanities citation index had the lowest overlap with scie (32.79%).this overlap leads to an increase in the volume of outputs and the visibility of some fields. the highest increase of outputs and the visibility occurred in the art and humanities fields is in contrast withthe initial outputs and the visibility of them. there was a converse tendency between the subject overlapand the fields of scie and ssci; however, the tendency of its overlap with the art and humanities fields, scie, and ssci fields was not significant.