Why is the gap so large?


Rindermann & Thompson (2013). Ability rise in NAEP and narrowing ethnic gaps?. Intelligence.

Quote: Third, achievements of African Americans (Blacks) and Latin American Americans (Hispanics) rose more than those of European Americans (Whites) (similarly Bishop, 1989): dec Black =3.04, dec Hispan = 2.27 and dec White = 1.29 IQ, leading to more narrow gaps (White – Hispanic-difference from diff = 11.59 to 8.46 IQ, White –Black-difference from diff= 16.33 to 9.94 IQ). Ability distributions are today more overlapping than in the past. This US development could be compared to the developments in Europe where ability gaps between natives and immigrants from Arabian-Muslim and African countries have narrowed, but haven’t disappeared (te Nijenhuis, de Jong, Evers, & van der Flier, 2004). But there are three disappointments: White–Black-gap-narrowing stopped in the late eighties, as also found by other measures (highest educational degrees, Graduate Record Exam, SAT, ACT; Barton & Coley, 2010; Farron, 2010, pp. 293-295; Neal, 2006; Rushton & Jensen, 2006 ); the competence level of high ability groups has hardly risen; and school leaver (17-year olds) have hardly achieved any gains.

The problem be …

(a) The gap was at its maximal in the 1970s — as such, comparisons between the present day gap and the 1970s gap don’t summarize well the historic trend. Refer to 100 years of Testing Negro Intelligence for a comprehensive review of studies.

(b) To make an achievement test, cognitive ability test comparison — NAEP-IQ, not NAEP-ACH — one has to correct for test correlations as discussed by Sackett and Ellingson (2000) and as done by Sackett and Shen (2008) and by Chuck (2013).

(c) The NAEP MAIN doesn’t support the narrative that “the gap” narrowed. Below are the NAEP age 17 LTT (Math and Reading) gaps from the 1970s to 2012 and the NAEP grade 12 MAIN (Civics, Economics, Geography, Math, Reading, Science, History, Vocabulary, and Writing) gaps from 2009 to 2012. The NAEP LTT (Math + Reading) gaps have indeed narrowed to d= 0.78, which is equivalent to a composite (or NAEP-IQ) d-value of 0.85 (assuming a subtest correlation of 0.7), yet the NAEP main (Civics to Writing) average d-value remains at 0.95, which is equivalent to a composite (or NAEP-IQ) d-value of 1.12.



There are two possibilities here: (1) NAEP average main gaps are “inflated” by the inclusion of exotic tests such as Civics (compare, though, with ASVAB tests such as Mechanics) or (2) both NAEP LTT and NAEP Reading tests are “deflated” by a program of teaching to the tests. It’s difficult to adjudicate between these alternatives. In support of hypothesis (2): the NAEP reading, SAT reading correlation (r=0.74) is significantly lower than the NAEP math, SAT math correlation (r=.91) — see Moran et al. — and the B/W narrowing has primarily occurred in NAEP reading, not NAEP math, etc; it is quite possible, then, that NAEP reading tests have lost some of their g-loading. In support of hypothesis (1), a similar pattern of differences (reading<math<science) has been found in the ECLS (1998-2007) and was found by Sackett and Shen (2008).

It’s not clear the me, though, that reading achievement differences better index the gap than the composite of all achievement difference taken together.

(d) Importantly, the gaps are still much larger than what would be predicted by the maximal reasonable genetic hypothesis d, genetic g =1. Assume heritability of g, age 17 = 0.7 & r (g x achievement) = 0.7. The achievement gap would be, on the account of genetic g alone: 0.84 x 0.7 = d = 0.59.

So, the question is: Why is the gap still so large? On the most general level, the answer is differential inheritance (environmental and genetic). Hence both the NAEP Main and LTT show that school identified mixed race individuals who self ID as Black and White score intermediate to school identified monoracial individuals — see, for example, It Could be Culture, part I/II (The NAEP Black-Mixed-White gap).


Moran et al. NAEP 12th Grade Preparedness Re Establishing a Statistical Relationship between NAEP and SAT

Sackett, Paul R., and Winny Shen. “Subgroup differences on cognitive tests in contexts other than personnel selection.” Implications of Organizational Staffing and High Stakes 31 (2009): 323.

Sackett, Paul R., and Jill E. Ellingson. “THE EFFECTS OF FORMING MULTI‐PREDICTOR COMPOSITES ON GROUP DIFFERENCES AND ADVERSE IMPACT.” Personnel Psychology 50.3 (2006): 707-721

This entry was posted in Uncategorized. Bookmark the permalink.

2 Responses to Why is the gap so large?

  1. nooffensebut says:

    Interesting. Dr. Ferguson wants us to believe that rap music stopped further black progress. The White-Hispanic-SAT-score gap also declined from the mid-seventies to the late eighties. Does this also reflect a seventies peak gap? Could this be an extended nuclear-annihilation-fear-induced sixties hangover?

  2. 猛虎 says:

    Lynn has a new paper. The sample age is 5 yrs, but blacks averaged 90 IQ points. I am somewhat surprised that bengladeshi and and pakistani scored even lower than blacks. Oh, and black caribbean average 96.6 points. There is also another very interesting paper here. The authors speculated that while education is associated with higher IQ, it could be that “increases in later life IQ score may not have been caused by more education; instead, post age-11 increases in intelligence may themselves cause individuals to stay longer in education”. Very important, is that educational gains are not associated with processing speed (RT or IT). This probably means that “education’s effects are possibly limited to specific aspects of intelligence tests, such as knowledge and perhaps reasoning. Education’s positive effects on the gaining and deployment of knowledge may not, then, extend to the more basic informationprocessing tasks that were tested here”. This would be my conclusion, as well. What do you think ? This study seems to be in line with Plomin new paper, Nature, nurture, and expertise, about “what is” and “what could be”. Incidentally, this guy, I mean Plomin, he really writes a lot. I found so many papers with his name on it. Anyway, I think the second paper is important because it is usually said that the likely cause of the BW gap is due to a difference in education level and opportunities.

    Have you noticed James Thompson blog ? He has a couple of articles recently, and they are interesting. You should really have a look.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s