The book then goes on to measure a number of things that relate to the students' success at
solving mathematical problems, and the statistics show a number of differences between the
two groups. On page 240 three measures of differences in performance are described, and
the differences are said to be "quite substantial." The implication is left, though it is never
actually stated, that the differences in performance are related to the difference in the
teaching methods that were used on the two groups.