A very interesting study on women defending themselves from rape and the success rates of these methods
Women who used non violent methods of resistance (crying, pleading, etc) were raped about 96% of the time.
Women who used forceful verbal resistance (yelling, screaming) were raped about half the time.
Running works better then yelling as the women who ran were raped about 15% of the time.
Forceful physical resistance is slightly more successful than running. Those women were raped 14% of the time. Striking was more successful than pushing or wrestling.
Finally, women who resisted using a knife or a gun were raped less than 1% of the time. I really think that figure speaks for itself.
A New Way to Resist Rape http://medind.nic.in/jal/t07/i4/jalt07i4p99.pdf