Child age | Mean | Standard deviation | Correlation | |||
8 | 10 | 12 | 14 | |||
8 | 21.8 | 2.3 | 0.64 | 0.66 | 0.67 | |
10 | 23.4 | 2.4 | 0.68 | 0.70 | ||
12 | 24.9 | 2.6 | 0.72 | |||
14 | 26.1 | 2.7 |