Columbia subject headings:
Academic achievement--United States--States--Statistics.
Mathematical ability--Testing--Statistics.
Mathematics--Study and teaching--United States--States--Statistics.
Harvard subject headings:
Academic achievement--United States--States--Statistics.
Mathematical ability--Testing--Statistics.
Mathematics--Study and teaching--United States--States--Statistics.
Princeton subject headings:
Academic achievement--Iowa--Statistics.
Mathematical ability--Testing--Statistics.
Mathematics--Study and teaching--Iowa--Statistics.
Statistics.