[Update: I found NLSY 79 and NLSY 97 AFQT scores broken down by generation in Hansen et al. (2010). The scores from the two studies were not directly comparable, so Hansen et al. transformed them in the manner discussed by Altonji et al. (2008). Hansen et al. did not present standard deviations so I used those for the full survey sample presented in Altonji et al. (2008). Also, Hansen et al. limited the analysis to males. This might have affected the score distribution but the 3rd generation ‘97 scores reported were only slightly different from those which I found using both sexes, so any effect, if existent, is likely small. The category "Children of immigrants" includes all individuals who had at least one foreign born parent. Based on the demographic distributions in the ‘60s and ‘80s, we can deduce that one and two thirds, respectively, of the Hispanic children of immigrants were of the 1st and the 2nd generation. Children of natives, of course, are of the 3rd + generation.
For the IQ estimates I used the 97’ native White score as a norm. It can be seen that 1st and 2nd generation Hispanics narrowed the H/W gap by 2 points, while 3rd and 4th + Hispanics narrowed it by 4 points.
A commentator suggested that there could have been a cohort effect such to render the '79 and ‘97 Hispanic samples incomparable – e.g., due to changes in immigration patterns, etc. If such an effect occurred, it was probably small, at least for the ‘children of natives,’ as the ‘97 ‘children of the natives’ would represent -- though were not -- the offspring of 2nd + generation Hispanics in the '79 cohort. The latter comprised, approximately, 90% of the ’79 Hispanic sample. So there is not much room for an immigrant effect, again, at least for the children of natives. To investigate this issue further, we can look at the CNSLY which was based on the actual children of the NLSY ‘79 cohort. The scores, to note, are not readily comparable because completely different assessments were used. The data were taken from Fryer (2010) and Winship (2003). Averaging the math, reading, and PPVT scores, the magnitude the W/H gap is 8 points, identical to that between native Hispanics and Whites in the 97’ survey. As noted, though, these scores are not directly comparable. Specifically the assessments used, particularly the PIAT tests, had significantly lower g-loadings than the AFQT and so, as with academic achievement scores, do not capture the full magnitude of the difference. Based on the discussion in Murray (2006) concerning the relation between PIAT and IQ scores with respect to the Black-White gap, I estimated that the H/W score differences on these tests is characteristic of a full scale H/W IQ gap of 10 points; this is the same magnitude of difference found based on the more g loaded PPVT in this same sample. Based on this estimate, the differential between 3rd generation Whites and Hispanics narrowed 2 points.
Taken together, we can conclude that there was at least a 2 point narrowing between 3rd + generation Whites and Hispanic between 1979 and 1997. And that the magnitude of this narrowing could have been as high as 4 points.
Now, there is one factor that has yet to be taken into account. As has been noted, there seems to be an intermarriage effect, such that the offsprings of one Hispanic and one non-Hispanic White perform notably superior to the offsprings of two Hispanics from the same generational cohort. This effect, by whatever mechanism it works (e.g., cultural integration, genetic assimilation, etc.) could account for a portion of the found narrowing. This topic will have to be further explored latter.]
Following up with my last post, I looked at the performance of third generation Hispanics in the NLSY 97. Below, ASVAB is the AFQT and PIAT is the Peabody Individual Achievement Test, which was given to different waves in 1999, 2000, 2001, and 2002. I aggregated the PIAT scores across years. The race/ethnic and generation scores are normed on those of Whites (in italics). For both tests, the White-Hispanic gap dropped to 0.5 SD by the third generation. It appears that Ron Unz’s mysterious “prominent rightwing blogger” was not in error, at least if discussion is restricted to the relative performance of 3rd generation Hispanics. (I defined “3rd generation” as noted below.) Search variables and sources are noted. (Lest you ask, the large reduction in numbers going from the full sample (“ALL”) to the 3rd generation sample was largely due to missing information.)
(Interestingly, the NLSY contains detailed information on parental ethnic heritage, in the classic sense of “Italian” and “Dutch,” not merely the euphemistic sense of “race.” Interested investigators can refer themselves to page 92 and 112 of “Screener, Household Roster, and Non-Resident Roster Questionnaire Parent Questionnaire” for the relevant variables.)