In fact, some impotence researchers assert that the success rates of prostaglandin may not be much better than the success rates of placebos.
Placebos may be working just as well as prostaglandin. 
mnli hypothesis: Placebos may be working just as well as prostaglandin.  premise: In fact, some impotence researchers assert that the success rates of prostaglandin may not be much better than the success rates of placebos.