There is some great data in the paper that is well analyzed and presented. The author's interpretation of the results would have been improved if they recognized that IQ was heritable which simply explains the higher number of MR children born to women with lower educational status. What is more interesting though is that having a black mother is a risk factor for MR after correcting for educational attainment. Other factors being equal, a college educated black mother has the same risk of having a retarded child as a white mother with a high school education.
To fully address this problem, we may need to consider intergenerational risk factors, which involve the mother’s own developmental history. Maternal intergenerational factors clearly play a role in low birthweight ..., and it is likely that other aspects of development, including cognitive development, also have an intergenerational component .
Intergenerational risk factors that affect cognitive development. What could those be?
16 comments:
Nice find. I was going to point out that 1SD would predict a much higher odds ratio, but then I remembered this discussion: http://www.lagriffedulion.f2s.com/retard.htm
Thanks. The Chapman (2008) paper has unadjusted rates by race for the entire state of Florida and hence La Griffe's sampling problems with the Baltimore data should be absent. I may blog more about this later (feel free to beat me to it) but Chapman still observed only about half of the 7 fold difference you should observe based on bell curves. I am not sure why.
IQ was heritable which simply explains the higher number of MR children born to women with lower educational status
You are referring to mild retardation.
Profound mental retardation, OTOH, is not correlated with IQ. Most cases of profound retardation involve the mother being older (over 40). Older means less healthy means a much higher chance for the chromosomes to not line up properly in the baby. But completely random all the same. As is my understanding.
Any explanation for this? --
The correlation between retardation rate and percent support for Sauerbrey [a conservative candidate] was extraordinary, with correlation coefficients of 0.88 and 0.90 for the black and white rates, respectively. Correlation coefficients this large are almost unheard of in social science. It is a pretty safe bet that right-leaning school districts will find more of their children retarded than their left-leaning counterparts, a fact that leftists have long suspected.
[From La Griffe du Lion that Chuck linked-to]
"You are referring to mild retardation."
The paper I referred showed a strong correlation between race and severe retardation "without neurological symptoms". That is retardation once you omit the downs, fragile X etc. Retardation with CNS symptoms had the primary correlation with old moms.
As I reread LaGriffe's point I cannot tell whether he thinks dumb people are conservatives or that conservatives run school districts that classify as retarded. Both are plausible.
This sentence:
We looked for correlations between political philosophy and the tendency to classify children "retarded.
does suggest he means "conservative-run school districts classify as retarded more".
Good point but the data about Baltimore threw me off. I do not think of that as a conservative county. Regardless Chapman seems to have all of the MR data for Florida but I do not expect him to replicate La Griffe's analysis
I'm looking for any race and regression to the mean papers; I consider this strong direct support of the HH. If you come across any, let me know.
Rushton and Jensen refer to some evidence in the "G factor" in their PPL article (2005). All of them use SES as a proxy for IQ though.
Here is the PPL article. http://www.udel.edu/educ/gottfredson/30years/Rushton-Jensen30years.pdf
This is the phenomenon that got Arthur Jensen started working on IQ and race in the mid-1960s: a former student of his who was teaching asked him to come look at students who had been classified as retarded. The white kids tended to be FLKs, while the black kids tended to look and act pretty normal on the playground. But IQ tests were equally good predictors of a lot of measures for both races.
Would the intergenerational factors be a reference to epigenetics?
M,
Maybe in his mind but he was vague enough so that his readers could infer "the legacy of slavery." Possible intergenerational factors would be genetics but if you could rule that out then epigenetics is possible.
"Thanks. The Chapman (2008) paper has unadjusted rates by race for the entire state of Florida"
After you mentioned this, I read the paper; now it seems that I don't have access to it. Would you mind looking it up and checking the SDs -- the authors list percents, but as you likely know, you can easily transform that to SD: http://www.lagriffedulion.f2s.com/excel.htm
Hi Chuck,
Below should do it. Let me know if you can't read it. I can send you the PDF also.
Table 1. Administrative Prevalence of Mental
Retardation by Level and Race/Ethnicity per 1000
Mental retardation per 1000
Race N Mild Mod Sever
Black 90,993 39.6 5.5 1.4
White 195,737 8.8 2.6 0.9
Hispanic 36,212 9.1 3.1 1.3
Other 4,889 5.1 3.1 0.6
Total 327,831 17.3 3.4 1.0
With respect to Mild, Moderate, and Severe MR:
Plomin and Spinath, 2004. Intelligence: Genetics, Genes, and Genomics
A second issue concerns the relationship between the normal and abnormal. For example, to what extent is mild mental retardation (MMR) genetically distinct from the rest of the distribution of intelligence? ...In contrast, siblings of mildly retarded children (1.2% of the sample) tend to have lower than average IQ scores (see Figure 4, solid line). The average IQ for these siblings of mildly retarded children was only 85. Similar findings—that MMR is familial but moderate and severe retardation are not familial—also emerged from the largest family study of MMR, which considered 80,000 relatives of 289 mentally retarded individuals (Reed & Reed, 1965).
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