Well not to do a Livia and jobgasm,
but if you understand odds and probability, you also understand that increasing the number of fixed variables doesn't change the fact that more chances = more likelihood. I mean if you want actual figures;
Condom failure is 98% (thus odds of failure are 50/1)
The pill has a "perfect" (lab) rate of 99% but a "real terms" rate of 91%, we'll split the difference and call that 95% or 20/1
The combined odds therefore are 50/1x20/1 = 1000/1, or 99.99% effective.
Which means if a couple is together for 10 years and has sex 100 times per year, using condoms and the pill, it is
probable that they will experience one failure. I personally think with the best will in the world perfect usage is unlikely and even that 1000/1 figure is unrealistic, but I suppose with extreme vigilance possible. That doesn't really mean much in real world scenarios, though.
As most are only using one form of contraception the failure rate is 1 or 2 in 100, which means if a couple has sex 100 times a year, they will have 1 or 2 failures a year. If they have sex 200 times a year, they will have 2 to 4 failures. And so on. Again... you literally
cannot argue against the maths of probability, it's not possible. If it was the scumbags I work for wouldn't be in business
.