| Second-Stage Estimates. Dependent Variable: math-reading ratio | ||
| Ind. Variables | Coeff. | Coeff. |
| Hours of Sport (IV) | 0.031** (0.025) | 0.035** (0.041) |
| Father Education | 0.001 (0.987) | 0.001 (0.966) |
| Father Occupation | 0.001 (0.943) | 0.001 (0.988) |
| Mother Occupation | −0.002 (0.327) | −0.011 (0.614) |
| Month of Birth | 0.001 (0.998) | 0.001 (0.999) |
| Nationality | 0.006 (0.712) | 0.001 (0.772) |
| Region | −0.028*** (0.000) | −0.032*** (0.000) |
| High School Type | −0.013** (0.032) | −0.011** (0.039) |
| Observations. | 2834 | 2230 |