As indicated, all of the comparisons for the first three grades show A > R. This proportion drops as a negative function of grade level. As grade level increases, the proportion of comparisons in which A = R grows, and becomes equal to the proportion of comparisons showing A > R at around the eighth grade level. Reading excels only at the college and adult levels, where close to half of the comparisons show A < R.

The triangles in Figure 4 indicate the proportion of comparisons in which auding and reading performance is equal (not significantly different). Although limited data points restrict the certainty of this presentation, there appears to be an inverted-U relationship between grade level and the equivalence of auding and reading performance. This inversion reflects the increased numbers of comparisons at the college and adult level where reading surpasses auding performance (a point we will comment on later).