Impact of Industry Classification Schemes on Financial Research
This paper investigates industry classification systems. During the last 50 years there has been a considerable discussion of problems regarding the classification of economic data by industries. This paper also examines the structure and content of industrial classification schemes and how they affect financial research.
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http://econpapers.repec.org/scripts/redir.pl?u=http%3A%2F%2Fsfb649.wiwi.hu-berlin.de%2Fpapers%2Fpdf%2FSFB649DP2005-062.pdf;h=repec:hum:wpaper:sfb649dp2005-062