From Editing to Writing: Learning the Write Stuff 
At SAS Institute Inc., a leading software development corporation, the Documentation Development Division maintains separate staffs for writing and editing. Working as an editor and working as a writer require distinctly different skills in developing user documentation. In this paper, we discuss our experience making the transition from editing to writing: the differences between the jobs, the similarities, and how working as editors has benefited us as writers. We direct this paper to anyone interested in making the change, in either direction. While your situation may differ, we hope you find our experience informative.
Restivo, Kathryn A. and Philip R. Shelton. STC Proceedings (1994). Presentations>Editing>Writing