When observable measures such as socio-economic and health factors are adjusted, the IQ gap is substantially reduced yet a non-trivial difference remains. And while it is known that environmental factors are influenced by genetic factors and therefore should be not treated as pure environmental effects, an outcome that is typically ignored is that the education-matched blacks fall further behind in the IQ scores when education level increases.
Author: Meng Hu (Page 1 of 2)
In The Pattern Seekers: How Autism Drives Human Invention (2020), Baron-Cohen proposes the Systemizing Mechanism as an explanation for human progress through invention, from the first tools to the digital revolution. Autistic people tend to be hyper-systemizers, due to their repetitive behavior and obsessive interest. With their talent at spotting novel patterns which produce a potentially groundbreaking result, they have potential to be inventors. They are those who can’t help focusing on precision and detail and figure out how a system works, how to improve a system.
How much the 5 personality traits composing the Big Five contribute to social outcomes? Many studies examined the question but only a few also considered IQ. This article will only cover the studies which evaluate the Big Five while controlling for IQ.
A quick summary reads as follows: conscientiousness is associated with better income and health, extraversion inversely predicts delayed rewards, neuroticism negatively predicts health, perhaps none of these traits are related to academic achievement or occupation status and, finally, publication bias is a problem.
As reviewed in my previous article, the majority of studies on measurement bias, either on the item- or subtest-level, reached an agreement about the fairness of IQ test. Unfortunately, even among studies which use acceptable Differential Item Functioning (DIF) methods, the procedure was often sub-optimal. This probably leads to more spurious DIFs being detected.
The advantages (and shortcomings) of each DIF method are presented. The GSS data is used to compare the performance of the two best DIF methods, namely IRT and LCA, at detecting bias in the wordsum vocabulary test between whites and blacks.
This is a 2-part article. In this first part, the most important studies on internal test bias with respect to racial groups in the item-level, subtest-level and construct-level are reviewed. The proposed causes will be discussed. Generally, the most commonly used IQ tests aren’t biased or only minimally biased as to be of no practical value.
The best methodologies with an application using the Wordsum GSS for the Black-White group will be discussed in the second part of the article : DIF Review and Analysis of Racial Bias in Wordsum Test using IRT and LCA.
The idea that schooling raises intelligence still prevails. The influential study review of Ceci (1991) concluded that schooling has a strong impact on IQ scores despite his final warning that observed score does not equate real intelligence. After, many more studies were published, including latent factor modeling and quasi-experimental designs. It is unclear whether education truly improves general intelligence modeled as latent factor or whether long-lasting IQ gain involves far transfer effect. More likely, the answer to all of these questions is negative.
Back in 2014 I wrote an extensive review of studies on the income mobility rate over time and across countries and discussed whether it truly fits the Great Gatsby Curve, a term based on the observation of the negative relationship between mobility and inequality, that is considered by many as unfair because it implies that higher inequality causes lower mobility. However I did not consider Black-White difference in mobility. Because mobility and inequality are interrelated, I will cover both topics here.
It’s been almost 50 years now that the famous study of Willerman et al. (1974) has been published. This study is regularly cited as one of the most convincing evidence against the hereditarian hypothesis, despite strong emphasis by hereditarians on the failure of experimental efforts to raise IQ (more specifically, g) and population differences magnifying during adolescence or adulthood due to increasing heritability with age (Jensen, 1998, pp. 333-344, 359, 474; See Malloy  for a case of a stability model with respect to the Black-White gap). Caution about this study is now vindicated. The data used by Willerman also revealed a pattern: the IQ deficits related to having a Black mother seem to vanish over time (Hu, 2022). Continue reading
Or nearly so. I was planning to publish that blog article for the 31th December 2014. As you can see, I failed in this task, and didn’t finish in the right time. Anyway, I wrote this article, mainly because I am bothered that when people cite The Bell Curve the typical opponent responds with a link toward Wikipedia, specifically the part related to the “controversy” of The Bell Curve. It goes without saying that these persons did not read the books written in response to The Bell Curve. In fact, they have certainly read none of them. It is ridiculous to cite a book you didn’t read, but apparently, it does not bother many people, as I see.
For the 20 years of the book, I found appropriate to write a defense of the book. Or more precisely, a critical comment on the critics. I have decided to read carefully one of these books I can have access, and for what I have read here and there, it is probably the best book ever written against The Bell Curve. I know that Richard Lynn (1999) has already written a review before. But I wanted to go into the details. The title of the book I’m reviewing is :
Devlin, B. (1997). Intelligence, Genes and Success: Scientists Respond to the Bell Curve. Springer.
In fact, I have read that book some time ago, but didn’t find the need to read everything in detail. And I was unwilling to write a lengthy review. But I have changed my mind because of some nasty cowards.
Here, I will explain how to use the so-called “Yhat” or predicted values of Y when doing regression (OLS, logistic and multilevel).
(Update 2017) This article is based on my paper: Hu, M. (2017). An update on the secular narrowing of the Black-White gap in the Wordsum vocabulary test (1974-2012). Mankind Quarterly, 58(2), 324-354. Continue reading