From Rolling Stone/"Rolling Stone and UVA: The Columbia University Graduate School of Journalism Report":

Erdely and her editors had hoped their investigation would sound an alarm about campus sexual assault and would challenge Virginia and other universities to do better. Instead, the magazine's failure may have spread the idea that many women invent rape allegations. (Social scientists analyzing crime records report that the rate of false rape allegations is 2 to 8 percent.) At the University of Virginia, "It's going to be more difficult now to engage some people … because they have a preconceived notion that women lie about sexual assault," said Alex Pinkleton, a UVA student and rape survivor who was one of Erdely's sources.

From the cited study (False Allegations of Sexual Assualt: An Analysis of Ten Years of Reported Cases):

For example, the UCR stipulates that the category “unfounded” is reserved for “a complaint that is determined through investigation to be false or baseless. In other words, no crime occurred...The UCR guidelines also make clear that the category of “unfounded” is broader than the category of false allegation, since “unfounded” includes cases that are determined to be “baseless.” A case can be classified as “baseless” if, for example, a victim reports an incident that, while truthfully recounted, does not meet, in the eyes of investigators, the legal definition of a sexual assault. For example, if a victim reports to the police that she was raped while she was intoxicated, and truthfully states that she cannot clearly recall whether there was penetration, investigators might classify such a case as “baseless/unfounded.” This classification is clearly distinct from a case in which a victim deliberately fabricates an account of being raped, yet the “unfounded” category is very often equated with the category of “false allegation.”...

Only 42 cases (36.2%) were classified by the police as “founded”; the remaining 74 cases were classified as “unfounded"...

Of the 302 cases, 24% were “no-crimed” by the police for various reasons, but only 34% of those “no-crimed” cases were classified as false allegations...

Of the 483 cases examined, 123 were classified as “no-crime” by the police, and 53 (10.9%) were categorized as false allegations...

Most pertinent to this discussion, one classification was, “Unfounded/False (based on investigative findings that a crime did not occur, according to UCR criteria).” This category was defined to include only cases that were determined, on the basis of evidence collected, to be false allegations. A separate category, “Unfounded/Baseless (elements of the crime were not met, but not false, according to UCR criteria),” was created for cases that do not meet the UCR criteria for a false report but where the events do not constitute a crime according to the state’s penal code. The MAD data, analyzed but not yet published, are included here with permission of the researchers (K. Lonsway & J. Archambault, personal communication, August 19, 2008). Of the 2,059 cases analyzed from law enforcement agencies in the participating communities, 140 (6.8%) were classified by law enforcement as false reports (Lonsway & Archambault, 2008...

The authors of this study have extensive feminist/social justice credentials. Their bios:

Lori Gardinier, MSW, PhD, is the program director for the Human Services Major at Northeastern University in Boston, Massachusetts where she is also the founder of the Campus Center on Violence Against Women. She holds a master’s degree in social work from Boston University and a PhD from Northeastern University. She has practiced in the area of antipoverty/ social justice work in community-based settings and as a counselor in organizations addressing intimate partner violence. Her most recent publication examines the Paid Family Leave Campaign in Massachusetts as a social movement.

Sarah C. Nicksa, MA, is a PhD candidate in the sociology program at Northeastern University. Her dissertation, entitled “Bystander Reactions to Witnessing Sexual Assault: The Impact of Gender, Community, and Social Learning,” will be completed in spring 2011. She regularly teaches “Violence in the Family” and is a medical advocate at the Boston Area Rape Crisis Center.

Ashley M. Cote is a graduate of Northeastern University’s College of Criminal Justice, where she focused on juvenile justice, security, and criminology. At Northeastern University, she was a member of the Campus Center on Violence Against Women, studied the effects of parental attachment on youth violence, and was elected a gubernatorial advisor for the Juvenile Justice Advisory Committee under the Massachusetts Executive Office of Public Safety and Security. She is currently employed at the Massachusetts General Hospital’s police, security, and outside services department and plans to earn a master’s in social work and urban leadership.

Link to the study (PDF):

http://www.icdv.idaho.gov/conference/handouts/False-Allegations.pdf