Often I’ve seen people use WORDSUM scores as a proxy for IQ. You may have seen it yourself, but wondered why people believe there is a correlation between the two. Razib Khan wrote up a nice post that explains it.
Every time I use the WORDSUM variable from the GSS people will complain that a score on a 10-question vocabulary test is not a good measure of intelligence. The reality is that “good” is too imprecise a term. The correlation between adult IQ and WORDSUM = 0.71. The source for this number is a 1980 paper, The Enduring Effects of Education on Verbal Skills.
It’s clearly tapping a cognitive dimension; vocabulary strongly correlates (.83) with the general intelligence factor: content validity. The WORDSUM correlation with the AGCT is within the range that IQ tests correlate with each other: concurrent validity. It is a reliable independent predictor and predicts external outcomes in a similar manner as other IQ tests: criterion validity.
I wouldn’t recommend it for clinical or admissions purposes, but the GSS is an adequate cognitive test for the purposes of the GSS.