Wednesday, March 02, 2011

More on jail inmate fertility

Jim Bowery made a good suggestion in the last post that I display averages by race. Here is the mean number of offspring by race and lifetime number of arrests (inmates are between 45 and 54):

Mean number of children

White (n = 259)
One lifetime arrest 3.26
Two 2.87
Three 2.54
Four 2.72
Five 2.67
Ten 2.71

Black (n = 250)
One 2.74
Two 3.15
Three 3.08
Four 3.37
Five 2.55
Ten 3.71

Family size does not decrease with more arrests for either race. The correlation between number of offspring and number of arrests is -.02 for whites and .02 for blacks; in other words, there is no relationship. According to the MIDUS Study of non-criminal men aged 45 or over, the mean number of children is 2.62.  Criminals have just as many, if not more, kids. (I'll look for prison inmate data--jail inmates have a lower average level of criminality.)


  1. Time spent in prison might be a more salient metric. A one-time murderer is probably going away longer than a multiple DUI offender.

  2. I have no science to back this up, but I can tell you this from experience... inmates in jails and prisons have more kids than the system will ever know. Your numbers are skewed because of children not reported. I knew of one young man that was 22 years old that had 4 children and another 3 women pregnant with his babies. I would wager that the number is much higher for felons than the general population by a large margin. look at the number of women and children on state aid. Where do you think the fathers are... or have been?

  3. Is it cheating to knock off the top (ten arrests) and bottom (0 arrest) samples?

    If not, then best fit for whites:

    1 3.26
    2 2.87
    3 2.54
    4 2.72
    5 2.67

    is 3.2*-1.3x with a coefficient of determination nearly .6; and for blacks:

    1 2.74
    2 3.15
    3 3.08
    4 3.37
    5 2.55

    the line is essentially 0 slope with a coefficient of determination of essentially 0 (0.006).

  4. That 3.2*-1.3x should, of course, be 3.2-1.3x

  5. Damn, I slipped a decimal place on the multiplier. Rather than -1.3 it should be -0.13:


    Anyway, it does look like a plausible model for white fertility drops off significantly with the number of arrests, with 0 arrests being part of a different model.

    What if a single arrest is just enough to make you into an "alpha" in the eyes of a significant number of females but not enough to subject you to the racially-biased sterilization effects of jail?


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