What Stone (1908) found "is summed up in the one word, diversity" (p. 90). He found great variability across school systems in average test scores, errors, time spent each week on arithmetic (whether or not homework time was included), and the "average ratio of time to abilities." He observed "a difference in course of study excellence which can hardly be put in words" (p. 90). Unwilling to use Rice's seat of the pants technique for ruling out factors that might be related to achievement, Stone ended up with a mound of correlation coefficients that pointed in various directions. Unlike Rice, Stone found some evidence that homework improved achievement. Because there seemed to be little relation between achievement and the time spent on instruction, he concluded that many systems must be wasting time on arithmetic.