Since the inception of the GSS, interviewers have recorded their impressions of respondents' apparent ability to comprehend the questions being asked them. The percentages, by wordsum intelligence groupings, who had a "good" grasp comprehending the questions being asked them (n = 24,111):
Language barriers do not present issues, as respondents not fluent in English were excluded from the GSS until 2006, when a Spanish version of the survey was also dispatched. This is evident in the gentle but steady increase over time in the percentage of respondents deemed to have "good" comprehension and a corresponding decrease in the percentage of respondents said to have "poor" comprehension--if a lack of English fluency was obfuscating the relationship, the average level of comprehension would be declining, not rising.
The effective range on the scale used to record respondents' socioeconomic status runs from 17.1 on the low-end to 97.2 on the high-end. Mean values by grouping:
And mean number of years of education:
Scarcely distinguishable from the distributions documented in The Bell Curve. The wordsum test is a relevant and incredibly useful proxy. Without it, GSS yields would be much less copious than they are.
GSS variables used: WORDSUM, COMPREND, SEI, EDUC