association ranges between 0.22 and 0.31. The strength of association when the unit of measure is a school or district in a large sample is in the range of 0.68.9 b. By contrast, and as shown in 1b, the correlation between reading scores in fall K and future academic performance is almost twice as high: 0.531 for individual students (or 0.569 when including math) and 0.986 to 0.996 for groups, depending on the size of the group. Obviously, poverty and incoming scores are cross‐correlated but our data set did not have free or reduced lunch counts for either the individual students or for the schools so we could not determine the degree of their association. It is difficult to affect poverty as a variable but incoming scores can be changed. Given the greater size of the correlation between kindergarten and Grade 5 scores, it is likely that if parents and school districts can increase low incoming scores, it is likely to erase much of the impact traditional attributed to poverty. 7. Impact of initial starting points in math using a simple correlation. Replicating the same analysis above but switching math scores for reading scores, we calculated the impact of initial math scores at kindergarten scores on subsequent academic math performance on an individual and group level as follows: a. By individuals: The degree of association of math scores in the fall of kindergarten of 51,781 students to the fall math scores of each subsequent year is 0.707 (Grade 1), 0.612 (Grade 2), 0.606 (Grade 2), 0.600 (Grade 4), and 0.594 (Grade 5). b. By percentile groups: The degree of association of average fall kindergarten and fall Grade 5 math scores is 0.995. Our database was 51,781 students, sorted by their kindergarten scores, divided into 100 groups of 517 students, and compared to the average scores of these same student groups in the fall of Grade 5. 10 8. Impact of initial starting points in math also using reading in a two‐variable reading prediction model. The degree of association of average fall kindergarten and average fall Grade 5 math scores of the 51,781 students is 0.989 with an r2 of 0.978. We derived this conclusion using the same process as for reading. That is, we sorted the 51,781 students into percentiles (that is, 100 groups of 517 each), based on their fall kindergarten math scores, then subdivided each of those 100 groups into quintiles based on their reading scores (thus generating 500 groups containing 103 students each). As before, we found that entry‐level reading skills are associated with later math skills. Using both reading and math at the individual level modestly improved model predictions (from 0.594 to 0.608 in Grade 5; see Sections 1a and 1b). 9. “Free” increases in math scores when reading scores increase. One of the consistent unpublished findings in previous research has been that, when reading scores improve, math scores also improve even though teachers may not be putting any additional focus on 9Catherine
E. Snow, M. Susan Burns, and Peg Griffin, eds., Preventing Reading Difficulty in Young Children (Washington, DC: National Research Council/National Academy Press, 1998), 126‐127. 10 The correlations slightly stronger for math and reading, the drop is greater in reading (drops by 0.16) than math (drops 0.11). For both subjects, most of the drop domes during kindergarten for reading (69%) and math (84%).
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