A Syntactic Approach To Readability
http://baywood.metapress.com/link.asp?target=contribution&id=PHUCGY8LJRLEVMNN
  access restricted (by the publisher) to members/subscribers/customers only
  peer-reviewed

Giles, Timothy D. and Brian Still
Journal of Technical Writing and Communication
2005

Abstract:

Focusing on the issue of readability, this article examines problems that readability formulas present to the technical communicator, especially in terms of interaction with government agencies, and focuses on readability formula requirements mandated by The Office of Health and Industry programs [OHIP] for medical technology product support literature. Because the Flesch Reading Ease and the Flesch-Kincaid formulas are widely available, they are probably the ones most frequently used. Contemporary readability scholars have overlooked the Golub Syntactic Density Formula, which evaluates prose according to a sentence's syntax at a deeper level than the number of words per sentence and the number of syllables per word. The authors recommend it as a tool for evaluating readability. How it might be applied with current computer applications is discussed.