PolitiFact’s Truth-O-Meter examined the claim from a White House official who said “98 percent of Catholic women have used contraception,” and found the claim to be “mostly true.” The USCCB argued in return that the number was much lower, but Politifact held that the bishop’s mathematical error was in considering a “snapshot in time” rather than behavior over time, concluding that “most women [over time] would find occasion to take advantage of the new co-pay-free contraceptive rule.”
This bothered me, and I remembered something I read in Robert Ruff’s 1988 book, Aborting Planned Parenthood. The widely held assumption that birth control “works” is not considered over time, but on a “snapshot in time” percentage.
Stick with me, this is not a boring “how geeky art I” post…
I want to show you something significant, and I’m giving you the tools to use it in a debate.
Typical-use failure rates are defined as the expected number of pregnancies in the first year per 100 women using the method. That means that for the pill with a typical-use failure rate of 8, that of 100 women using the pill, in a single year 8 of them will become pregnant. A single year.
But what about the ever-so-important “over time” predictions demanded by PolitiFact? If we are going to consider how many women will use birth control over time, then shouldn’t we also consider how effective it is over time, rather than in a snap shot of a single year? Let’s take a look by simply using the reported typical use failure rates the contraception folks report for the first year, and extrapolating them mathematically over time.
Remember those lessons from algebra class about determining the probability of getting 16 heads if you flip a coin 100 times? That can be easily calculated by using the binomial probability formula. Here’s an online calculator so anyone can check the math.
The Binomial Probability Formula
The binomial probability formula is the same formula you use when trying to find the probability of getting X number of heads when you flip a coin, say, 100 times. In other words, we want to figure out that if 8 out of 100 women are expected to get pregnant in one year, then how many should we expect to get pregnant in 5 or 10 years.
It’s called the Exact Binomial Probability formula, a straightforward formula with no assumptions made. You can use this calculator.
N = the number of years to consider a woman using birth control (1, 5, 10, etc.)
k = the number of pregnancies, so enter 1
p = the probability, see here for women, see here for teens. Enter the decimal form. If the failure rate is 8 out of 100, enter .08. If the failure rate is 15 out of 100, enter .15.
The number to read is the line that says, “P: 1 or more out of N.”
So Let’s Have a Look at the Numbers
The typical-use failure rate for the pill is 8%, in one year 8 out of 100 women using the pill in a typical way will get pregnant, but the numbers are much higher extrapolated over time. It’s even worse for condom use.
||# Women out of 100 that will get pregnant 1 or more times:
|Birth Control Method
||Typical-Use Failure Rate
8 out of 100 women will have unintended pregnancies in one year, but 34 of those same 100 women will have unintended pregnancies in five years, and more than half in ten years. Condom use has an even higher failure rate, so typical-use of condoms over five years actually makes a woman more likely to get pregnant than not. Over ten year’s time, it practically ensures unintended pregnancy. And what about teens? Teens are not as careful so the failure rates are higher.
||# Teens out of 100 that will get pregnant 1 or more times:
|Birth Control Method
||Typical-Use Failure Rate
Fifteen is the age considered the beginning of the reproductive lifetime, so out of 100 fifteen-year-old girls who begin using birth control, 36 of them will be pregnant by the time they are age twenty. If their sexual behavior and birth control use remains the same, most will be pregnant by the time they are age twenty-five. (Disease is a whole ‘nother story.)
Birth control does not prevent unintended pregnancy, but over time it actually makes it more likely, whether the woman is a teen or not, just based on the failure rates reported. Birth control is claimed to be the “responsible” thing to do if you aren’t going to be responsible in the first place, so frankly these numbers are not surprising. Of course it logically follows that if someone’s idea of being responsible is to use a pill/device when you don’t want to be responsible in the first place, then responsible use of said pill/device is probably an unwarranted expectation. Yeah, read that last sentence one more time, which is probably why they don’t report failure rates beyond the first year.
Back to the HHS Mandate. If the argument is that most women will use birth control, therefore, it should be paid for by insurance, then what are they trying to get us to pay for? That women will have unintended pregnancies?
It would seem so to the mathematically-aware, knowing-the-truth-doesn’t-make-you-a-geek observer.
People become accustomed to a lifestyle of sex without consequences along with an ignorance of the human body, and they think of unintended pregnancies as unwanted pregnancies, and we know what the advertised “cure” for that “disease” is – abortion. Besides, when you consider that the contraception and abortion activists also predict that 1 in 3 women in their reproductive lifetime will have an abortion (notice folks, here they speak in terms over time when it suits their argument), aren’t they really admitting that they already know birth control fails?
Birth control over time normalizes abortion.
We knew that, but this calculation proves it using their own reported estimates. Of course the other alternative is to be “fixed” like an irrational animal with implants, injections or surgery, something Catholics also oppose because we are taught that to be fully human we must use our intellect and will to strive to be virtuous. Animals, as you know, can’t do math either.
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