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agapewolf
Guest
I am not missing this point…because it doesn’t follow logic.I think the point you are missing is that 2 pregnancies per 100 couples per year assumes that the couple doesn’t deliberately select fertile or infertile days.
Presumably if the OP were to have sex with a condom, this is what he would do, so the 2% chance per year would be a good measure of risk for him.
The 2 pregnancies per 100 couples per year could only have happened when the couple had sex on a fertile day. For the purpose of finding out the chance of getting pregnant with a condom on a fertile day, you need to know how many sex acts the 100 couples had on fertile days.
The study would be bad if there were disproportionately few sex acts on fertile days, like say only 2. But, as long as this was not the case, it doesn’t matter.
Even if each couple only had fertile sex 10 times in the whole year. That’s 100 couples * 10 fertile sex days per couple = 1000. And of those 2 pregnancies. (And this is a rough estimate because once a couple gets pregnant, they can no longer have fertile sex. But since only 2 get pregnant, this difference doesn’t have an effect although it would if say all got pregnant.)
What the “effectiveness” is supposed to be testing is the ability of condom to stop sperm. It’s getting credit for stopping sperm when it really didn’t… but conception wasn’t possible… so its getting credit for stopping sperm even though it didn’t.