Bringing a Stat Book to a Culture Fight

Bringing a Stat Book to a Culture Fight October 16, 2011

Comments are still a little bit in flux here.  Because Disqus was causing problems, it’s been stripped off and we’re back to plain old wordpress comments until things get sorted out.  On the plus side, this means that all the previously vanished comments are back!

Oh, and speaking of comments, today I want to point you to a conversation that’s going on over at Marc’s Bad Catholic blog here at Patheos.  Marc wrote a post called “10 Reason the Pill Sucks” and, although I disagree with several of the listed reasons, my epidemiological background makes me focus on claim one: The Pill doubles a woman’s chance of breast cancer.

It’s always a bad idea to cite only the percent increase in risk, especially if you’re talking about a rare disease.  It’s done all the time, even by science journalists, and it’s always misleading.  Here’s why.

Imagine there’s some disease that naturally occurs in 20% of the population.  If a certain exposure doubles the risk, 40% of people exposed will get sick.  Yikes!

Or imagine a disease that naturally occurs in 0.02% of the population.  If a certain exposure doubles the risk, 0.04% of people exposed will get sick.  Depending on what you’re using the exposure for, it may not be worth it to give it up.

Talking only about the percent increase in risk (which you may also see referred to as a twofold or n-fold increase) doesn’t help me make accurate choices to mitigate risk.  I need to know what the risk normally is, without the exposure, so I can think about the magnitude of the increase.*

The best way to talk about increased risk is just to tell me the baseline incidence rate and then the incidence rate among exposed people.  It can also be helpful to talk about the population attributable risk – a way of estimating how many cases of the disease wouldn’t exist if it weren’t for the exposure.

You’ll notice, after all this stat talk, I still haven’t weighed in on the question Marc originally brought up – whether the risk of breast cancer conditional on hormonal contraception use is too high.  To a certain extent, that’s a subjective question — individuals may weight the positive effects of the Pill differently and have different risk tolerances.  But there’s no way to get into that discussion until you have better risk parameters on hand than percent increase.

I said all of this in the comment thread of Marc’s post, so you can see some of the responses there or discuss his other reasons for being anti-contraception.


*[One commenter on Mark’s post thought the doubling number was helpful because it could just be applied to the usual estimates of breast cancer incidence.  I went through the paper fulltext and found that the doubling only applied to one subtype of breast cancer (triple negative).  All the other kinds they looked at had no significant increase in risk.  I have no idea what the incidence rate is for the triple negative subtype, so the doubling number is still not helpful.

This confusion highlights another flaw in citing percent increase; people may become confused about what incidence rate it applies to.  Always cite your baseline.]

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  • Any argument that takes the form of “ladies, this thing that you think is good for you is really sexist, and I as a man am here to educate you about it,” (which describes about half of his points) automatically makes me hit the back button.

  • maggie

    I don’t know what the incidence rate of triple negative breast cancers is (still working on a pubmed search for that one), but I do know that women with triple negative breast ca are significantly more likely to be under 40 and African-Americans- and that it’s more aggressive and has lower survival rates. These features may make it more relevant to a discussion of the Pill’s overall risk since obviously most women taking it are in that under-40 age group.

  • dbp

    Trying this again, this time in the right thread….

    From here:

    About 15 to 20 percent of breast cancers are triple negative or basal-like [26,35-41]. These tumors tend to occur more often in younger women and African American women (more on race/ethnicity and subtypes of breast cancer) [26,38-41,43-44]. And, most BRCA1 breast cancers and many BRCA2 breast cancers are both triple negative and basal-like [43,46].

    Triple negative/basal-like tumors are often aggressive and have a poorer prognosis compared to the estrogen receptor-positive subtypes (luminal A and luminal B tumors) [26,36,38,45].

    From what I find, incidence of breast cancer is about 12%, so let’s call the beastie under consideration something which will affect about 2% of all women. If that doubles to 4%, which side of the spectrum does that fall on? Or, if we assume that this is with use of the pill at saturation, then reverse the question: what if we could cut the 2% of all women down to 1%? Either way, you’re two orders of magnitude above your 0.02% example.

    Put still another way: “About 39,520 women will die from breast cancer.” So we can conservatively ballpark maybe 7000-8000 women dying a year from this type of breast cancer (conservatively, because this is described as more aggressive and having a poorer prognosis than other types, which means it probably results in a proportion of mortality higher than its base incidence).


    I (a man, incidentally) have seen responses similar to yours from people who come down pretty strong on the feminist side– don’t know anything about your own particular bent, so take this for what it’s worth. I can sympathize with the instinctive reaction, but honestly I think it runs off the rails more often than not.

    First, I will mention just incidentally that it’s a logical fallacy (the ad hominem). Either the points are correct or they aren’t, but his being a man doesn’t have anything to do with that.

    Second, to recap his points:

    1) Breast cancer
    2) How it came to be
    3) Disruption of the biochemistry of attraction
    4) Correlation with divorce
    5) Effect on libido of both partners
    6) Two effects on men (removal of natural objects of attraction, and pressures to shift from ‘masculine’ to ‘feminine’ modes of self-expression
    7) Abortifacient side-effects
    8) Ecological side-effects
    9) The burden (of use and potential side-effects) falling mostly on women
    10) Increase in abortion (the conventional side, over and above #7).

    There are things in here that are arguable, certainly, but to see in “about half his points” a sexist feigned anti-sexism is just silly.

  • To be fair, I also see in several of his points (particularly #7 and #10, and possibly more if I were more familiar with the others) factual inaccuracy.

    My point is, a man telling a women what’s misogynistic is condescending because guess what? Women know a lot more about misogyny than men do. We live with it every single day. Even if he happens to make roughly some of the same points as some feminists, it is still condescending for him to think that he knows so much more about the subject of sexism and has to educate us women. Because we’ve never considered these points, nor put in enough thought to come to the conclusion that imperfect as it is, the Pill might be better than the alternatives.

    He’s not saying, “here’s what I’ve learned from women about the Pill, and I’m going to tell it to men so that they don’t put all the burden of birth control on women,” or anything like that. He’s saying, “you women who use the Pill don’t know what’s best for you, but I do.” No thanks. If I want genuine feminist critique, I’ll get it from feminists.

  • dbp

    I don’t think it’s condescending at all. Like I said, either he’s right or wrong, and if he’s wrong, it’s not because he happens to have the wrong sort of genitalia. Telling someone they can’t talk about something because they’re Y instead of X is backwards regardless of what Y and X are in this particular case. What part of what he’s talking about requires a woman’s experience to be qualified to speak about? All you’re saying is that you can acknowledge (or reject on its merits) all 10 arguments and still come to the conclusion that the Pill’s OK. That’s your prerogative as a rational being. But, your response to him seems like a knee-jerk (even if it’s the product of real misogyny you face every day, the possibility of which I do not dispute) that misses its mark in this case. I’m afraid to say it even seems like a dodge.

    Information isn’t male or female. He doesn’t have to have learned about the Pill from women to have learned true things about the Pill (and many studies underlying the information he cites were, surprise, concerned with women, not men). It isn’t condescending to collect all that information into one place, even when a man does it. If the information is actually wrong, then engage with it in those terms instead.

    On another note, people do things that are bad for them all the time– smoking being the easiest and least controversial counterexample. Surely you don’t mean to pretend otherwise?

  • “I don’t think it’s condescending at all.”

    Fine. I disagree.

    “Like I said, either he’s right or wrong, and if he’s wrong, it’s not because he happens to have the wrong sort of genitalia.”

    As it turns out, he is wrong and/or underinformed about a lot of things.

    “What part of what he’s talking about requires a woman’s experience to be qualified to speak about?”

    What I’m arguing is that he’s failing to acknowledge women’s experience of sexism when he deigns to tell us what we should consider sexist. We KNOW about sexism! We don’t need men to tell us about it! We know that it’s unfair that we bear almost the sole burden of birth control! We don’t do that because we think it’s awesome; we do it because it beats the available alternatives. But he’s acting like he just discovered all this and needs to tell women about it RIGHT AWAY ZOMG.

    This isn’t listening to women; it’s talking at us.

    “I’m afraid to say it even seems like a dodge.”

    Whatever. I’m not trying to impress you.

  • dbp


    “As it turns out, he is wrong and/or underinformed about a lot of things.”

    Very well, but you didn’t cite even one concrete instance; you only vaguely alluded (and only after I challenged you) to knowledge that #7 and #10 show “factual inaccuracy,” but haven’t offered any evidence to back even that up. I’d say the ball is still in your court.

    Furthermore, you yourself add parenthetically, “and possibly more if I were more familiar with the others.” This implies that you aren’t familiar enough with his other points to know whether the points are accurate or not. If Marc’s sources are reliable, it follows that he, in fact, knows more about the potential harmful side-effects than you do. And, in point of fact, it would seem that lots of women are neither confident in their knowledge about oral contraceptives nor happy about their lack of confidence:

    Of the 305 women who returned the questionnaire, 93% had used the OCP at some time in their lives, with 32% reporting current usage. Only 50% of women reported satisfaction with previously accessed information about the OCP. Less than 40% of the sample reported a high level of confidence in their knowledge of the risks, benefits, and side effects of OCP use.

    So it seems it isn’t clear that all women are making as informed a decision as you seem to imply.

  • dbp

    (Continued) Now, I’m very willing to believe that there’s a lot about sexism he doesn’t know. To my knowledge, he didn’t claim that the Pill is the only place misogyny is encountered, nor that he’s the best person to tell you all about misogyny in its fullness. He’s discussing a specific, and very common, drug, and demonstrating that there are all sorts of bad things that go along with it, and disproportionately so for women.

    Now, this alone can probably be reasonably-supposed valuable enough to support Marc’s posting it– even if he is a man. But he actually goes a step further and offers a possible alternative at the end of his post– one concerning which even medical professionals seem to be undereducated about and information about which is not widely distributed with normal contraceptive counseling:

    Most physicians in our study underestimated the effectiveness of NFP methods, and only a small proportion of physicians provide information about NFP during contraceptive
    counselling. Physicians need better understanding of modern methods of NFP to provide evidence-based contraceptive counselling to selected highly motivated patients who prefer
    NFP as a contraceptive choice.

    Remember that his post is first and foremost not about sexism, but about the Pill and arguments against its use. There actually is a scientifically-verified lack of knowledge about this contraceptive method and available alternatives. Your comments don’t respond to Marc on the merits of the argument (and in fact rather indulges in an ad hominem fallacy), make a false assertion that all users of the Pill are making fully informed decisions, don’t bring any new information to the argument that might obviate his point, and fail to support your rebuttal to points you claim are incorrect. That’s why they read like knee-jerk anti-sexism leveled at the wrong target.

  • Please don’t take my simple statement that I don’t like being told by a man what I should consider sexist and turn it into an interrogation. It’s exhausting.

    The man makes broad, sweeping statements about the Pill’s effect on male and female sexuality, and cites freaking Time magazine as his only source for them. Twice. No, I’m not terribly knowledgeable about those areas, but neither is he.

    I’ve talked about some of the problems with #7 in the comments to that post.

    I never made the claim that women know all about the possible side effects of the Pill, so don’t claim that I did. I said that women know about *misogyny*. Which we do. We don’t need men to explain it to us. I’m white. If I tried to explain racism to an African-American, I’d be an insulting jackass.

  • dbp, I’d say I’m sorry I didn’t write a dissertation on what’s wrong with the post, but I’m not really. I debunk anti-contraception arguments ALL THE TIME, most of them pretty specious. That wasn’t my purpose here; I’d like a break from it, frankly. I just wanted to express my frustration at the particular form the post took. I’m comfortable with leaving it at that.

    Leah, sorry for veering so crazily off-topic!

  • dbp


    “I never made the claim that women know all about the possible side effects of the Pill, so don’t claim that I did.”

    What I was responding to was this: “We don’t do that because we think it’s awesome; we do it because it beats the available alternatives.” This makes it sound like a completely informed decision, when the data would seem to show otherwise.

    But since you’d rather not have that conversation, I’m content to let it rest. I have no particular connection to Marc, and am not endorsing all his statements.

    The reason I responded to you is that I object to the idea that it must be a sign of either sexism or condescension even when we try to take women’s side in arguments; even when what we say is primarily in the realm of objective facts that should be equally accessible to men rather than about the subjective and personal, first-hand experience of misogyny that, certainly, men cannot have; even in the face of evidence that women, in some cases, may not be fully informed about an issue which we might have pertinent information to share; even when we don’t pretend that there can be no other considerations which might affect a woman’s ultimate judgment about the matter and when we acknowledge her right to make that judgment as she sees fit; and even when we explicitly address our statements to men as well as to women (as you claim Marc is not doing; yet in the post in question he does in fact write things like, “Husbands, boyfriends, men, do you understand that when you make sure your lover is on the Pill, you increase her risk of cancer?”).

    So, fine, I understand you felt put off by what he wrote, and you expressed it here. But I think your accusations against him (not the factual ones about his reasons specifically– I’m not defending them particularly) are ill-founded.

    And however insulting you find his attitude, yours is equally so when you fence off debate concerning factual and objective matters–which might matter to us men very personally and dearly because of the effects we see from them in our loved ones, and because we care whether our society is just or not–for the irrelevant reasons of the sex of the debater.