How to Lie with Statistics: Response to Progressive Alaska Part 2

With Sarah Palin's resignation, the direction of this blog has taken a temporary detour. It has been impossible over the last five days to keep the focus on "Babygate," and ignore the larger implications of her resignation and the "hoopla" surrounding it. And I don't think anyone wants me to.

Is Sarah Palin still a viable national entity? I do not believe so. Her history of quitting is quite striking: she quit as mayor of Wasilla to run for Lt. Governor of Alaska (a race she lost.) She quit a major Alaskan appointment, that of chairman of the Alaska Oil and Gas Conservation Commission. Although a great deal has been made of this "protest" resignation, the reasoning is eerily similar to her resignation as governor. She could be more effective from outside of the commission than actually on it. But numerous people in Alaska have put a more mundane spin on this resignation. The job was reportedly a real full-time job with real full-time work. She was expected to produce, not just be a figurehead; she just was not up to it.

And now - with a year and a half left as governor she quit for reasons that she stated as mostly personal: things like adults being mean to Trig. (Whether her stated reasons are all there are is of course open for question, but for now let's take her at her word.)

But that still leaves us with the initial question of this blog, and as I said in the "Sarah Quits; We Won't" post several days ago, I do not intend to let this issue slide. I believe that there still is enough of a chance that Palin might emerge on the national stage that the truth about Trig's birth must come to light, once and for all. I still believe that the elements of the Republican Party that gave us Sarah Palin and kept her on the ticket (while - I strongly suspect - becoming aware at some point in the campaign that she had faked the pregnancy) must be held accountable.

I am continuing now with the multi-part post I began last week, before the resignation, in which I am attempting to consider a very long post written by Lee Tompkins, a labor and delivery nurse, last January, and reprinted several weeks ago by the blog Progressive Alaska.

I have received some criticism for doing this, including a comment from someone I respect, accusing me of doing nothing but "addressing nonsense arguments from a moron first posted months ago." But I disagree. These "nonsense arguments" form the basis of why some very reasonable people, who I do not think ARE morons, and who do not support Gov. Palin in general are still not on board with the idea that she faked a pregnancy, duping both Alaskans and the American people. And the topic of today's post - the Down Syndrome "proof" that Trig must be Sarah's - is one of the cornerstones of this.

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Here's the link to Part 1 in case I have new readers who have not seen it.

This is the second part of my very long post, addressing the points raised in Lee Tompkins' article. In this installment, I intend to (try to) debunk one of the most persistent (and incorrect) assumptions in this whole issue: that Trig's Down Syndrome virtually proves that Sarah is his mother. I do apologize for all the math and numbers here, and realize that at times it's difficult to follow. But the problem is that this statistical proof is cited so often without anyone even understanding the numbers, that they only way to reasonably confront it is with the calculators on the desk.

A couple of Google searches and it's not difficult to figure out that the likelihood of a Down's pregnancy in a 44-year old woman is 25 times greater than that of a teenager. Of course, overall more Down's babies are born in the younger age groups but that is reflective of the greater numbers of pregnancies occurring in younger women than older women. That statistic alone should be convincing enough, but it is probably not.

The writer's opinion here is clear. This statistic (i.e, that Sarah had a 25 times greater chance of having a baby with Down Syndrome) alone should virtually prove to us that Trig must be Sarah's.

This "proof" of Trig's parentage has haunted those of us searching for the truth since day one. Often people who appear to know virtually nothing about the "Who's Your Mommy?" controversy (except perhaps that there is one), all can unfailingly summon this one "fact": Trig MUST be Sarah's because older women have babies with Down Syndrome. I've seen it a thousand times in comments on blogs, gotten hundreds of emails that say the same thing. Trig has Down Syndrome; this proves Trig is Sarah's. Case closed.

What is the reality?

It IS more likely, much more likely in fact, that a woman over 40, on a given pregnancy, will conceive a child with Down Syndrome than a woman less than 20. No dispute. But every year in the U.S. about 300 babies with Down Syndrome are born to women under 20. Not a huge number, but not insignificant either. This is about the same number as babies born deaf to women under 20 (who have no family history of deafness.) Would we disbelieve the story if we are told that a teen mother would have a deaf child?

Furthermore, those who repeat this statistical argument ignore another, equally powerful one in the opposite direction, one that I have never heard confronted head-on, with real numbers, regarding this situation, and that is that Sarah Palin, at 43, had a far FAR lower chance of ever having a baby at all.

Natural fertility drops sharply after age 40, a fact that is now nearly lost in the perception of the general public. Every week, it seems, yet another celebrity well into her forties has a baby. Several in the last few years (Geena Davis and Nancy Grace to name two) have been quite near, even at, fifty. But many - probably the majority - of these women have had these babies with fertility assistance: injections to stimulate ovulation, hormonal support after conception to compensate for a body that is really too old to be having children, and in many (perhaps most) cases where the mother is over 42 or 43, the use of donor eggs. However, these private details are typically not made public, so the public knows only that a baby has been born. They have no realistic clue just how difficult and expensive it was to achieve that.

In addition, women are routinely counseled to stay on contraceptives into their late forties, yet are only rarely advised by their physicians as to how low their actual chances of becoming pregnant are. Because of this, the erroneous perceptions that older mothers conceive often and easily and that pregnancy after forty is likely are firmly ensconced into our national consciousness. (This is much to the dismay and sad disappointment of many women in their late thirties and early forties, who have delayed childbearing and are now discovering that the effects that aging has on fertility often cannot be overcome even with help.)

In reality, what are the chances that a 43 year old woman, who is presumably practicing some sort of contraception and who is not "trying" to get pregnant, in fact will get pregnant at all and then carry that child to near term? The odds are actually extremely poor.

Women who are over 40 face a double whammy: fertility drops every year, and simultaneously rates of miscarriage rise.

Consider the following:
1. At age 40, a woman who is demonstrably fertile still only has a 1 in 20 chance (5%) of getting pregnant in any given cycle. A teen has a 20-30% chance of getting pregnant in a given cycle. And that's age 40. Sarah Palin was 3 1/2 years older than this.
2. At age 40, even using in vitro fertilization, (involving medical assistance with precise timing and hormonal support) the pregnancy rate per cycle is only 10%.
3. The chances of a woman over 40 who is trying to get pregnant via in vitro using her own "old" eggs is one/sixth of that of getting pregnant with younger "donor" eggs. In fact, most clinics will not even use the eggs of women over 40 because the failure rate is so unacceptably high.
4. 50% of pregnancies in women 42-43 years of age end in miscarriage, compared with only 10% for women less than 30.
5. By age 40, 33% of previously fertile couples are infertile, and this rises to 90% by age 45. At age 43 1/2 (the age at which Sarah Palin is alleged to have become pregnant) the chances of her even still being fertile at all were only about 1 in 3. Read that again. Statistics tell us that Sarah Palin had a 66% chance of not being able to get pregnant at all.

Plus - the Palins have been clear that the pregnancy was unexpected, that their baby-having days were over, and that they were not trying to have a child. This can only mean one thing: some sort of family planning method was being used. This would have cut Sarah Palin's already-low chances of becoming pregnant much farther. Oral contraceptives are 95% plus successful in preventing pregnancy. Even condoms are supposedly 85-90% effective in preventing pregnancy if used correctly.

So let's whip out the calculators here. For this little calculation, I am going to ignore the issue of contraception. We can't know what sort of birth control anyone in this equation was using or how consistently and rigorously it was used. So, to simplify things, I am going to, using statistics, attempt to answer the following question. If you have a 43 year old woman and a 17 year old woman who are both "letting nature take its course" (i.e., both sexually active and neither using contraceptives) , what are the relative chances that, in a given single month, each will get pregnant and carry the baby to term?

In a given monthly cycle, at age 40, a fertile woman has a 5% (1 in 20) chance of conceiving. I could not find a comparable statistic for a 43 year old, so we'll use 5% while stipulating that the actual number is certainly lower for a 43 year old. However, don't forget that this is a fertile woman. By age 43, 2/3rds of previously fertile woman are infertile. This reduces that ACTUAL monthly chances of conceiving for a 43 year old to 5% x .33 or 1.66%. A random sexually active 43 year old woman not practicing contraception has only a 1 in 60 chance of getting pregnant each month.

A 17 year old has a 20-30% chance of conceiving per month. For simplicity, let's split that down the middle and say 25%. A random sexually active 17 year old woman not practicing contraception has a 1 in 4 chance of getting pregnant per month.

In other words - the seventeen year old's chances of getting pregnant in a given month are 15 times higher.

But that's not the end of the story because now, the much higher rates of miscarriage come into play.

The 43 year old has at least a 50% of chance of miscarrying the baby. This cuts the success rate in half, to .8%. The chance that a 43 year old woman will get pregnant in a single month and carry the child to term is less than 1 in 100.

The 17 year old, meanwhile, has a 7% chance of miscarriage. (Sources cite numbers any where from 5% to 10% - I am splitting the difference.) This gives us a successful pregnancy rate per month for the 17 year old of 23%. The chance that a 17 year old woman will get pregnant in a single month and carry the child to term is 23 in 100.

.8% for the 43 year old versus 23% for the 17 year old. 29 times more likely. Ironically, quite close to the often quoted statistic that Down Syndrome is 25 times more likely in the older mother. So read that again. Understand what it really says. Yes, Down Syndrome is 25 times more likely in an older mother, but SUCCESSFUL PREGNANCY is 29 times more likely in the younger mother.

And don't forget, this result is for women NOT using contraceptives (Palin almost certainly was) plus this result was obtained using fertility rates for 40 year olds ( Palin was 43.) Both of these factors would reduce this already - low number even farther in this specific case.

Younger women can have babies with Down Syndrome, though it's rare. Older women can have babies with no medical assistance or support, though it's rare. But what the statistics do show is that those who USE Down Syndrome rates to argue that Trig must be Sarah's are totally missing the other bus: We could just as easily use overall fertility rates to argue that Trig must be Bristol's.

So return to the paragraph I quoted from Lee Tompkins article to start this post, now rewritten:

A couple of Google searches and it's not difficult to figure out that the likelihood of a pregnancy carried to term in a 17-year old woman is 29 times greater than that of a 43 year old. That statistic alone should be convincing enough, but it is probably not.

Feels funny when the shoe is on the other foot, doesn't it?

Now, to be explicitly clear: statistics are merely a guideline. Statistics do not prove anything either way. Trig has Down Syndrome. This in no way proves he is Sarah's. Trig exists. This in no way proves he is Bristol's (or any other younger mother's.)

And that's what needs to be taken away from this post.

PART 3 COMING SOON