Most important predictor of reduced family size?

Which factor reduces family size the most? Below are the standardized OLS regression coefficients for a sample of whites ages 40-59:

Standardized OLS regression coefficients

Education -.23*
Income .10*
IQ .00
Church attendance .10*
Belief in God .06*
Political conservatism .06*

*p < .05, two-tail test

Education reduces fertility more than any factor. IQ has no net impact. Look at how income has a significant positive effect on family size. Not surprisingly, religiosity and conservatism are associated with more children.

Improving general intelligence with pharmacological intervention

From the journal Intelligence:

Cognitive enhancing substances such as amphetamine and modafinil have become popular in recent years to improve acute cognitive performance particularly in environments in which enhanced cognition or intelligence is required. Nutraceutical nootropics, which are natural substances that have the ability to bring about acute or chronic changes in cognition have also been gaining popularity in a range of settings and applications including the workplace, driving and in the amelioration of age related cognitive decline. Huperzine A, Vinpocetine, Acetyl-l-carnitine, Rhodiola Rosea and Alpha-lipoic Acid are popular nutritional supplements that have shown promising benefits in improving a range of biological (e.g., blood flow, anti-inflammatory, anti-oxidant, and direct neurotransmitter effects) and cognitive processes from in vitro, animal and human clinical research. We report here the first human randomized clinical trial for cognition in which we administer a combination of Huperzine A, Vinpocetine, Acetyl-l-carnitine, R. Rosea and Alpha-lipoic acid (called Ceretrophin) vs placebo. Sixty participants (40 females and 20 males, with a mean age of 45.4 years, SD = 12.6) completed either the odd or even items from the Raven Advanced Progressive Matrices (APM) at baseline and the opposite odd or even items at week 4 after consuming either the combination nootropic or placebo. A significant study visit (time) × treatment condition interaction was found: F (1, 57) = 7.279, p = 0.009, partial η2 = .113, with paired samples t-tests revealing a significant improvement in mean APM score from baseline to retest (week 4) (t(34) = − 4.045, p < .001) for the Ceretrophin™ group. Improvements in APM scores could be attributed to the active intervention over the placebo, indicating that the treatment improved general intelligence. Implications for improving our understanding of the biological basis of intelligence and pharmacologically improving human cognition are discussed.

Do really skinny women have fewer children?

Does extreme thinness cause a woman to be less fertile? I looked at women ages 40-59 who participated in the MIDUS Study. I limited the sample to people with at least a 4-year degree. Here are the mean number of children by body mass index (BMI) classification (sample size = 369):

Mean number of children

BMI under 20 1.45
20-29 2.10
30-39 2.08

A BMI under 20 is extreme in this sample: this group is only 3 percent of the total sample. And you can see that they have fewer kids.

Lesbian cops?

There is a stereotype that female cops are lesbians. Is it true?

Using GSS data (sample size = 129) 15 percent of female law enforcement officers are homosexual or bisexual. According the the same survey, only 2.7 percent of all women are homosexual or bisexual. 

How about gay cops? Do you remember the officer from the Village People? Out of 102 male officers, ZERO are homosexual or bisexual.

Conservative racism

These are results from a new Gallup poll. Explain to me how conservatives are such bigots when they like a black man more than eight out of nine white candidates (or potential candidates). And Cain isn't even white on the inside like Obama. He's a real black man.

Sex and bad vision

Looking at ADD Health data, I see that 36.9 percent of young males wear eyeglasses, contacts or both. The number for young females is 53.4 percent. The difference is statistically significant. The pattern is the same for all races. Since this is an adolescent/young adult sample, I assumed the sex difference is due to the earlier maturation of girls, but the gap is just as big for those in their mid-20s. How do we explain this? Male stubbornness? Male hunting/warfare?

Blacks and terrorism

According to this new Pew poll, native-born blacks Muslims are more likely to have favorable views of terrorists than other Muslims. Evidently, Islam attracts anti-American blacks and encourages their alienation. On the other hand, a low percentage of actual terrorists have been native-born blacks. This is consistent with the black tendency to talk more than act.

Hi Mom

I need to post something. You'd think I have a Jewish mother, or something. She worries about me all the time, but doesn't want to bother me calling too often, plus sometimes I'm hard to reach. So she checks my blog. If he's posting, she tells herself, at least I know he's not dead.

Blacks are more narcissistic

In a new study in the Journal of Research in Personality, it was found that, compared to whites, blacks have a higher average score on several measures of narcissism. Going from large differences to small ones, blacks are much more self-absorbed (d = .83); entitled (d = .61); they are more likely to be grandiose exhibitionists (d = .57); to see themselves as good leaders (d = .45); to feel superior (d = .37); to think they can fool most people (d = .29); and to try to avoid rejection at all costs (d = .24).

Having been given the title of Archetypical Victim, blacks are very prone to thinking of themselves as special. But with a high heritability of .64, narcissism might be a racial trait.

Religion and interest in a career in science

Does growing up in a religiously affiliated home discourage going into a scientific field?

Using GSS data, I divided respondents into natural scientists and everyone else. I then divided people into those who had a religion at age 16 versus those with no religion. To control for IQ, I limited the sample to people who scored between 7 and 10 out of 10 on a vocabulary test (sample size = 6,479). .6 percent of those from homes with no religion became scientists. By contrast, 1.4 percent of people from families with a religion grew up to become natural scientists.

The GSS offers no evidence that religion discourages an interest in a career in science.

Skin color and educational level among blacks

ADD Health interviewers judged the skin color of respondents as black, dark brown, medium brown, light brown, or white. Limiting the sample to just African Americans, let's treat the measure as a rough indicator of the amount of European ancestry. Here is mean educational level by skin color (sample size = 1,211):

Mean educational level

Black 12.8
Dark brown 13.0
Medium brown 13.3*
Light brown 13.5*
White 12.8

*significantly higher than black category


Medium- and light-brown blacks are significantly more educated than black-skinned African Americans. White blacks--only 16 respondents--are the exception to the trend.

Personality traits and obesity

New from the Journal of Personality and Social Psychology:

Personality traits contribute to health outcomes, in part through their association with major controllable risk factors, such as obesity. Body weight, in turn, reflects our behaviors and lifestyle and contributes to the way we perceive ourselves and others. In this study, the authors use data from a large (N = 1,988) longitudinal study that spanned more than 50 years to examine how personality traits are associated with multiple measures of adiposity and with fluctuations in body mass index (BMI). Using 14,531 anthropometric assessments, the authors modeled the trajectory of BMI across adulthood and tested whether personality predicted its rate of change. Measured concurrently, participants higher on Neuroticism or Extraversion or lower on Conscientiousness had higher BMI; these associations replicated across body fat, waist, and hip circumference. The strongest association was found for the impulsivity facet: Participants who scored in the top 10% of impulsivity weighed, on average, 11Kg more than those in the bottom 10%. Longitudinally, high Neuroticism and low Conscientiousness, and the facets of these traits related to difficulty with impulse control, were associated with weight fluctuations, measured as the variability in weight over time. Finally, low Agreeableness and impulsivity-related traits predicted a greater increase in BMI across the adult life span. BMI was mostly unrelated to change in personality traits. Personality traits are defined by cognitive, emotional, and behavioral patterns that likely contribute to unhealthy weight and difficulties with weight management. Such associations may elucidate the role of personality traits in disease progression and may help to design more effective interventions.