Figure 1.

Longitudinal actor–partner interdependence model of alcohol intoxication frequency for dyads distinguished by relative partner age. a1_o = initial stability of individual behavior for older child; a1_y = initial stability of individual behavior for younger child; a2_o = subsequent stability of individual behavior for older child; a2_y = subsequent stability of individual behavior for younger child; p1_o = initial partner influence for older child; p1_y = initial partner influence for younger child; p2_o = subsequent partner influence for older child; p2y = subsequent partner influence for younger child. c1 = Time 1 dyadic similarity; c2 = Time 2 residual similarity; c3 = Time 3 residual similarity. U = residual variance in older child’s intoxication frequency at Time 2; V = residual variance in younger child’s intoxication frequency at Time 2; W = residual variance in older child’s intoxication frequency at Time 3; Z = residual variance in younger child’s intoxication frequency at Time 3.