Table 2.
Descriptive statistics of the measures: Means and SD’s (between brackets).
| Grade 3 | Grade 4 | Grade 5 | Grade 6 | Total | |
|---|---|---|---|---|---|
| One-step symbolica | 24.0 | 39.0 | 63.3 | 74.3 | 49.0 |
| (19.35) | (21.09) | (24.33) | (18.77) | (28.86) | |
| One-step standard WPa | 21.6 | 37.8 | 65.1 | 75.6 | 48.8 |
| (19.90) | (24.36) | (25.78) | (20.09) | (31.23) | |
| One-step non-standard WPa | 18.5 | 35.1 | 57.6 | 73.1 | 45.0 |
| (20.29) | (23.01) | (27.85) | (20.84) | (31.20) | |
| Two-step standard WPa | 8.8 | 24.7 | 49.6 | 64.1 | 35.6 |
| (12.67) | (22.14) | (29.14) | (27.06) | (31.77) | |
| Two-step non-standard WPa | 8.0 | 22.1 | 44.6 | 58.1 | 32.2 |
| (13.50) | (20.68) | (29.61) | (25.26) | (29.95) | |
| Working memoryb | 0.463 | 0.522 | 0.576 | 0.606 | 0.538 |
| (0.1470) | (0.1293) | (0.1187) | (0.1205) | (0.1409) | |
| Non-verbal reasoningc | 34.6 | 36.5 | 41.4 | 42.0 | 38.4 |
| (6.60) | (7.23) | (5.50) | (5.83) | (7.10) | |
| Reading comprehension (MOCCA)d | 7.8 | 11.4 | 13.4 | 15.3 | 11.8 |
| (4.37) | (4.30) | (3.88) | (3.20) | (4.87) | |
| Reading comprehension (CITO)e | 3.20 | 2.91 | 2.91 | 3.10 | 3.03 |
| (1.446) | (1.508) | (1.379) | (1.452) | (1.451) |
a
Percentage correct on the different problem types in the arithmetic task (0–100).
b
Mean proportion correct on the backward recall items of the Monkey Game (0–1).
c
Number of items correct in the Raven SPM (0–60).
d
Number correct on the MOCCA (0–20).
e
Grade-specific norm score CITO reading comprehension test (1=lowest quintile; 5=highest quintile).