Regardless, these factors are in a 1-to-1 relationship for around 99% of schoolchildren in the third grade "aged 9 years old on average" including, presumably,

Regardless, these factors are in a 1-to-1 relationship for around 99% of schoolchildren in the third grade "aged 9 years old on average" including, presumably, every single child studied in this study. Discussion of the specific differences, or of the other cases, might have substantial merit... but seem less than productive on this particular occasion as the topic is at best only tangentially related.