In light of Ron Unz’s assertion that the Hispanic-White (non-hispanic) differential has greatly narrowed in recent years, I decided to examine the change in the magnitude by generation. Numerous samples over the past three generations have consistently point to a gap of between 0.5 and 0.8 standard deviations. The largest analysis to date was conducted by Roth et al. A meta-analytic general intelligence gap of 0.72 SD was found for the 70s through 90s:
It should be noted that Spearman’s hypothesis has generally been found to hold for the the White-Hispanic gap. According to this hypothesis, the magnitude of the differential is correlated with the general intelligence-loadings of the tests. When evaluating the evidence this should be kept in mind.
Now, as noted, the evidence to data points to a difference of between 0.5 and 0.8 SD. However, there is a continual flow of Hispanic immigrants to the US; as such it’s possible that a narrowing of the difference is being masked by this continual inflow. Perhaps second and third generation Hispanics, against whom there should be little cultural bias, have greatly narrowed or even eliminated the difference, but this remarkable fact has gone unnoticed due to the under-performance of recent Hispanic immigrants, who are handicapped by a limited familiarity with English. This is a plausible scenario. To evaluate this possibility I looked at the cognitive ability differences by generation in The National Longitudinal Study of Adolescent Health (1994-1994), Program for International Student Assessment (PISA) (2000,2009), Trends in International Mathematics and Science Study (TIMSS) (2007), Progress in International Reading Literacy Study (PIRLS) (2001, 2006), and the General Social Survey (GSS) (2002-2010). The Add health data contained a picture vocabulary test; PISA, TIMSS, and PIRLS contained math, reading, and science tests which are highly correlated with IQ (Lehrl, 2005); and the GSS contain a vocabulary test which is also highly correlated with IQ. Below is a summary of the standardized differences between 3rd+ generation Hispanics and 3rd+ generation Whites:
The differences ranges from 0.35 SD (GSS) to 0.77 SD (TIMSS grade 8 science). The average of the differences comes out to 0.61 SD or, when averaging PISA, TIMSS, and PIRLS tests scores per year, per grade (e.g., PISA 2009 MAth + Reading), 0.59 SD. This is not largely different from the general intelligence difference reported by Roth et al. (2001), which is notable given what was said about Spearman’s hypothesis. On re-analysis, Ron Unz’s claim concerning the difference in the GSS sample was upheld; this claim, though, was contradicted by all other samples. As for the GSS sample, it’s notable that the Black-White difference is also greatly reduced. Noted this, Murray (2007) has pointed out:
The GSS vocabulary test. GSS data are now available through the 2004 survey, 6 years longer than the observation period available to Huang and Hauser (2001), and they show a continuing decline in the B–W difference for persons born into the early 1980s (author’s analysis of the GSS). But if the question is whether black performance on the vocabulary test has improved, there is no inconsistency with the Woodcock–Johnson results. The GSS has an absolute scale of correct answers, from 0 to 10, and the vocabulary items have remained unchanged since the advent of the GSS. The highest black mean score, whether measured in a single birth year or in five-year aggregations, occurred among blacks born in 1945–1949. The decline in the B–W difference in the GSS vocabulary test for persons born since mid-century is entirely attributable to a decline in white performance, not improvement in black performance
This sample, then, is probably best to be treated with caution.
Two of the studies, the GSS and Add health, allowed Hispanic scores to be decomposed by nationality. For both studies I compared the Hispanics (aggregated) and Mexican scores. For third generation individuals no significant differences was found; this wasn’t surprising as Mexicans constitute over 2/3rds of third+ generation Hispanics. This implies that Hispanic scores can be used as a proxy for Mexican scores. Tables below:
For interested readers, the tables below contain the generational scores for PISA, TIMSS, and PIRLS.
Lehrl, 2005. PISA – ein weltweiter Intelligenz-Test. Geistig fit.