Predictive Metrics: How Long Will It Take?
http://www.stc.org/ConfProceed/2005/PDFs/0011.pdf

Pope, Mike and Sharon A. Meramore
STC Proceedings
2005

Abstract:

Presents a case study in which the authors develop methodology for calculating how long it will take a team of writers to produce a documentation set. The methodology takes into account different types of documentation and documentation quality, and accounts for variations in writer productivity.