Note: this post is a work in progress. The effect size is a statistic that quantifies the magnitude of the association between two variables. It is arguably the most important statistic reported in any study attempting to report the relationship between different variables. This purpose of this post is to aid in interpreting effect sizes, particularly from a social science perspective. There are several different kinds of statistics that are used to report effect sizes, […]
Most people are aware that there are significant disparities between blacks and whites in the United States with regard to a wide range of important social outcomes, including crime, income, education, poverty, welfare usage, etc. For almost every measurable metric of important life outcomes, blacks perform significantly worse than whites. In this post, I will cite studies showing that many of these disparities are likely caused by the significant cognitive differences between blacks and whites. I begin by illustrating a few examples of the disparities between blacks and whites with respect to important life outcomes. Then I briefly review evidence demonstrating the predictive validity and causal influence of cognitive ability for these outcomes. Next, I present data illustrating the scope and magnitude of the black-white cognitive ability gap. Finally, I provide evidence indicating that many of the aforementioned disparities between blacks and whites are (mostly) eliminated after controlling for youth cognitive ability.
In this post, I will consider some of the most commonly posited explanations of the black-white cognitive ability gap. Firstly, I consider what I call the Test Bias Hypothesis, which posits that black-white differences in cognitive test scores are the result of biased tests rather than genuine differences in cognitive ability. Secondly, I consider the Schooling Hypothesis, which holds that the cognitive ability gap is the result of differences in schooling between blacks and whites. Finally, I consider the Socioeconomic Hypothesis, which affirms that the cognitive ability gap is the result of the SES gap. I will argue that each of these hypotheses fail to adequately account for the cognitive ability gap. The predictions made by each of these hypotheses (insofar as they make predictions) are consistently falsified by the preponderance of data.
In this post, I will review studies that have attempted to account for the cognitive ability gap among children by controlling for a variety of factors, including parental socioeconomic status (SES), birth weight, home environment, parenting practices, etc. I will use these studies to determine what seem to be the most plausible candidate explanations of the gap. I end by reviewing some important issues for future investigation.
I began investigating potential investigating possible environmental causes of the cognitive ability gap in another post. I argued that common environmental explanations – test bias, schooling, socioeconomic status, and societal racism – failed to explain the gap. Because common environmental explanations fail, it may prove useful to consider non-environmental (i.e. genetic) explanations of the gap. I will perform this task in this post. First, I will clarify the meaning of estimates of the heritability of intelligence. Next, I criticize some common poor arguments against genetic explanations of the gap. Then I will consider some arguments for a genetic explanation of the gap that are related to the heritability of intelligence. I conclude that such arguments are not sufficient to make any conclusion either way about the cause of the gap. I end by detailing the kinds of direct data that should be used to confidently conclude whether and to what degree the cognitive ability gap is due to genetic differences.
In a previous post, I argued that the black-white cognitive ability gap is responsible for many of the undesirable social disparities that we find between blacks and whites in the United States – including disparities in income, education, occupation, and crime. This means that the cause of the cognitive ability gap is extremely important, as this informs how (and if) we can reduce these social disparities. In another post, I examined some arguments on whether the gap is due to genetic differences or environmental differences. In that post, I concluded that we must use direct data to quantify the degree to which the black-white cognitive ability gap is due to genetic differences vs environmental differences. In this post, I will attempt to review all such direct data. I conclude that a primarily environmental explanation of the gap is most compatible with all the relevant direct data.