William M. Briggs

Statistician to the Stars!

Having A Kid Worse Than Divorce Or Death? Wee P-values Say Yes

This woman is obviously sadder than she would have been had her husband died after divorcing her.

This woman is obviously sadder than she would have been had her husband died after divorcing her.

When I first ascend to Emperor, after throwing into the dungeon any within earshot who cannot speak a full sentence without using ‘like’, my first act will be to create a year-long moratorium on all science publishing.

I’ll do this out of kindness. The system is rigged to tempt people beyond endurance to write papers that are either (A) nonsense or (B) what everybody already knows re-packaged as “research.” This must be stopped because it is having a terrible effect on the sanity of the nation.

As proof, I offer the peer-reviewedParental Well-being Surrounding First Birth as a Determinant of Further Parity Progression” by Rachel Margolis and Mikko Myrskylä in the journal Demography, a paper which was announced by the Washington Post with the headline, “Parenthood is worse than divorce, unemployment — even the death of a partner“.

The Post’s headline is possibly the result of insanity; it is certainly nonsense.

Margolis and Myrskylä begin their Abstract with: “A major component driving cross-country fertility differences in the developed world is differences in the probability of having additional children among those who have one.”

This is false. Probability, in differences or straight up, doesn’t drive anything. Probability isn’t a cause, and neither can statistical models discern cause. Some thing or some things caused each couple to have each child. Probability won’t be one of these things.

But could a cause of not having more children be the dissatisfaction that arose from having previous children?

Yes; yes, of course. So obvious is this “yes” that we haven’t any need, unless we’re an academic forced to publish, to “study” the question.

It was “studied”, however, by Margolis and Myrskylä. Sort of. The pair looked at already existing data from a thing called the “German Socio-Economic Panel Study” containing answers given by folks to questions designed for other purposes. “We include in our analytical sample individuals whom we observe from three years before a first birth through at least two years after the first birth”. Only those couples who had kids were examined. Some of these couples (about 58%) had a second or third after the first.

The main outcome was having a second child paired with this question (which, again, had nothing per se to do with child-rearing):

Respondents were asked annually, “How satisfied are you with your life, all things considered?” Responses range from 0 (completely dissatisfied) to 10 (completely satisfied).

I wonder why they didn’t start the scale at -17? And go to 5 x π? Any time you see numbers put to non-numerical things (like attitudes) you know you’re in for a rough ride. Anyway, this data is massaged further, mostly by calling the answer given on this question “well being” and then pretending it was well-being.

Then they do this: I know it’s long, but please read it:

[1] We measure levels of subjective well-being over the transition to parenthood, measured from two years before a child is born until the year after a first birth…

[2] We capture the gain in well-being in anticipation of a first birth. First, we calculate a baseline level of life satisfaction for each respondent by averaging their life satisfaction level for three, four, and five years before a first birth. Then we sum deviations from this base level for the period two years before, one year before, and the year of first birth.

Finally:

[3] We calculate the size of the drop in subjective well-being around a first child’s birth. We measure the difference between the maximum level of life satisfaction before a child is born (from two years before the birth through the year the child’s birth is reported) and the minimum level of life satisfaction after the birth (measured in the year the child is reported and the year after the birth is reported). This is a continuous measure that ranges from 0 if there is no drop or a gain, to 9, the maximum drop we observe in the data. This measure captures the issues raised by new parents who reported that the most common high is just before or just after the child arrives and that the most common low is during the first year after birth.

Got it? Non-numerical things assigned numbers and then the numbers are manipulated in a quirky way…and finally submitted to an unjustifiable statistical model! Cox proportional hazards regressions (see their p. 1154) with linear and interactive effects. Because of course these things are additive to understanding the probability of having a second kid or not.

The results are presented as if the mean of a group applied to everybody in that group. That’s how the Washington Post took it. This unfortunate practice is so common that it’s not even seen as the problem it is. “Those who have a second birth gained more in life satisfaction around the time of a first child’s birth than those who stayed at parity…”

The Discussion begins, “A standing puzzle in demography is why fertility in many developed countries is so far below replacement level.” Puzzle? The answer is people aren’t having kids. Why? Contraception, abortion, this kind of nonsense, narcissism, both parents having jobs and chasing money, and all the rest which everybody already knows about.

I gave up and wished these authors would have done their study in the way I suggested yesterday. By making and verifying actual predictions.

10 Comments

  1. Determinant of Further Parity Progression? What’s that mean?

    :: after throwing into the dungeon any within earshot who cannot speak a full sentence without using ‘like’ :: I LIKE to think I can write, but I speak worse than I write. I might not get thrown immediately into a dungeon, but I’d probably be on probation.

    OT :: WhatsUpWithThat is making a big deal about the Pope instituting an annual World Day of Prayer for Creation. I’m underwhelmed by the gist of the story, but thought you might want to check it out

  2. We’re expecting our first kid in December. I sure hope I still love my family after science tells me that I’m not going to.

    As for both parents having jobs and chasing money…
    A lot of younger folks made poor decisions when they were young (because that is what the young do, and it’s what the experts told them to do). However, unlike poor decisions of older generations, these decisions involved thousands (or hundreds of thousands) of dollars of non-bankruptable debt.

    I would argue that fertility is down because of how expensive raising a middle-class family has become. In a way, only having children that you can afford is viewed by the right as a responsible thing – “don’t have a bunch of welfare babies,” and the left – “just another mouth to feed in this overpopulated world”.

    Money is all we have left to protect us – modern society has made it more and more difficult to maintain social support networks of real friends – superficiality rules the day. We’re more alone than we ever have been, so the only thing we an do is hope that our money will keep things going and be enough.

  3. There is a 100% probability that I will not be reading the full paper by Rachel Margolis and Mikko Myrskylä.

    On the other hand, after 30 years of marriage, the product of which is two grown married children and a grandchild on the way, there is also a 100% chance that I will not be sharing the paper by Rachel Margolis and Mikko Myrskylä with my children.

  4. Ye Olde Statistician

    August 13, 2015 at 10:48 am

    How did they distinguish the drop in reported satisfaction with life due to the baby and the drop in satisfaction due to society getting suckier? Oh, wait, they probably didn’t. Galileo’s “work of the intellect” is no longer much practiced.

  5. “Non-numerical things assigned numbers and then the numbers are manipulated in a quirky way…and finally submitted to an unjustifiable statistical model!”
    I thought that was standard operating procedure. The EPA claimed that exposure to second hand smoke caused lung cancer but no exposure was measured. People were asked about their exposure, a numerical value was assigned to the answer and the numbers were analyzed by statistics.

  6. But, the question, John Z, is how much that (100%) probability is driving your decisions not to read nor to share the paper.

  7. I’m glad I am too old to have children, so people will stop asking me about when it will happen.

  8. Okay, I’m confused. Where in the study does it look at unemployment, divorce and death? The study seems to be on why people stop at one child, nothing more. Am I missing something?

  9. Here is the solution that will never happen:

    1. Cut the appointments of academics by 50-75%
    2. Double the salaries of those that make the grade.
    3. No longer require academics to publish-or-perish. Teaching is fine.

    The problem at the moment is that any half wit can become an academic these days. Academics should be “top tier” individuals only. There should be a competitive regime for those limited positions.

    People wonder why academics are so incompetent when there are no motivations for them to be competent. I was asked to stay on in academia by my professors but why would I do that given the pay grade?

  10. acricketchirps:

    The probability is not driving the decision… the essence of the argument drives my decision. The essence causes me to reject the authors’ hypothesis and the basis for that rejection is captured in many of the comments made above already.

    That said, 100% of my rejection represents certainty only for large values of 100 …

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