Yeah, I do know redundant birth control can fail. I know my statistics. ;) But it's less likely than when using just a single form. In fact, I can tell you precisely how much less likely, as I just taught percents today and my birth control pills come with this nice and handy chart.
In one year of using condoms only, perfectly, 3% of women get pregnant, or typically 14%. One year of the Pill only they say 0.5% w/ perfect use and imperfect isn't listed. I'll make up 2% for my next stage of math. Assume the two are independent. To get pregnant using both methods, BOTH would have to fail. With perfect use, that would be 3%*0.5%=0.03*0.005=0.00015=0.015% chance of both methods failing. With typical use, 14%*2%=0.14*0.02=0.0028=0.28%, or just over 1 in 400. The chances of accidental pregnancy go from tiny to insignificant which makes me really shocked it happened to you.
I'm risk-adverse which is what led me to want to have the backup. Additionally, I'm intermittently on antibiotics for a skin condition, and they can decrease the effectiveness of birth control pills, so maybe I feel the condom's the backup for the pill? Yeah I know it's not perfect, but after getting out of college I realized how lucky I was that I didn't get pregnant with my first boyfriend. Withdrawal has a 4% pregnancy rate ideally, but 19% typically. Each year I had an 81% chance of NOT getting pregnant, so after two years of dating we had a 65.61% chance of NOT getting pregnant, or 34% chance that we would. I knew better, but I was sexually naive.
As a side note, I hope you find the humor in this statistical thought that crossed my mind. I wonder what percentage of people are pathological liars? If that percent's higher than the chance of you and your ex- having two forms of birth control fail simultaneously, then Occam's Razor says you were probably fibbing. Either that or you were nymphos, as the statistics don't account for frequency of sex. ;)
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timeasmymeasure
no subject
Date: 2005-11-07 03:42 pm (UTC)In one year of using condoms only, perfectly, 3% of women get pregnant, or typically 14%. One year of the Pill only they say 0.5% w/ perfect use and imperfect isn't listed. I'll make up 2% for my next stage of math. Assume the two are independent. To get pregnant using both methods, BOTH would have to fail. With perfect use, that would be 3%*0.5%=0.03*0.005=0.00015=0.015% chance of both methods failing. With typical use, 14%*2%=0.14*0.02=0.0028=0.28%, or just over 1 in 400. The chances of accidental pregnancy go from tiny to insignificant which makes me really shocked it happened to you.
I'm risk-adverse which is what led me to want to have the backup. Additionally, I'm intermittently on antibiotics for a skin condition, and they can decrease the effectiveness of birth control pills, so maybe I feel the condom's the backup for the pill? Yeah I know it's not perfect, but after getting out of college I realized how lucky I was that I didn't get pregnant with my first boyfriend. Withdrawal has a 4% pregnancy rate ideally, but 19% typically. Each year I had an 81% chance of NOT getting pregnant, so after two years of dating we had a 65.61% chance of NOT getting pregnant, or 34% chance that we would. I knew better, but I was sexually naive.
As a side note, I hope you find the humor in this statistical thought that crossed my mind. I wonder what percentage of people are pathological liars? If that percent's higher than the chance of you and your ex- having two forms of birth control fail simultaneously, then Occam's Razor says you were probably fibbing. Either that or you were nymphos, as the statistics don't account for frequency of sex. ;)