Effects of Technical Editing in Biomedical Journals: A Systematic Review
http://jama.ama-assn.org/cgi/content/full/287/21/2821
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  peer-reviewed

Wager, Elizabeth and Philippa Middleton
JAMA
2002

Abstract:

The 11 studies on technical editing indicate that it improves the readability of articles slightly (as measured by Gunning Fog and Flesch reading ease scores), may improve other aspects of their quality, can increase the accuracy of references and quotations, and raises the quality of abstracts. Supplying authors with abstract preparation instructions had no discernible effect.