Table 2.

Pearson correlations between SES, race, and verbal IQ test scores: 1978–2002 general social survey linked to the 2008 mortality via the National Death Index

	Latent trait scores, no DIF adjustment	Latent trait scores, DIF adjustment	Absolute difference	Relative difference
Gallup-Thorndike Verbal Intelligence test
Occupational prestige	0.32 (0.30 to 0.34)	0.11 (0.09 to 0.13)	0.21	2.91
Education	0.43 (0.41 to 0.45)	0.10 (0.08 to 0.12)	0.33	4.30
Income	0.25 (0.23 to 0.27)	0.09 (0.07 to 0.11)	0.14	2.78
Minority race/ethnicity	−0.21 (−0.19 to −0.23)	−0.05 (−0.03 to −0.07)	0.16	4.20
Wechsler Adult Intelligence Scales Revised Similarities test
Occupational Prestige	0.26 (0.23 to 0.32)	0.10 (0.06 to 0.14)	0.16	2.60
Education	0.40 (0.37 to 0.43)	0.16 (0.12 to 0.20)	0.24	2.50
Income	0.22 (0.18 to 0.26)	0.09 (0.05 to 0.13)	0.13	2.44
Minority race / ethnicity	−0.12 (−0.08 to −0.16)	−0.06 (−0.02 to −0.10)	0.06	2.00

Notes: Pearson correlations (r) with bootstrap 95% CIs. For minority race/ethnicity, positive correlations indicate higher VIQ scores among minorities, negative correlations indicate lower VIQ scores. Income in Year 2000 US dollars. Occupational Prestige is 1970 Socioeconomic Index for 1979–1989, 1980 SEI for 1990–2002 respondents. n=9381 for Gallup-Thorndike and 2444 for Similarities test.

DIF, Differential Item Functioning; VIQ, verbal IQ; SES, socioeconomic status.