Ratio of family members, N _fam to the square root of the number of background objects, , with Δ v _min ⩽ v _esc vs. (a) size of the progenitor and (b) inclination of the progenitor. In panel (a), symbol type indicates the subpopulation to which the progenitor belonged: triangles—cold classicals, squares—hot classicals, diamonds—inner classicals. The lines show N _fam/ N _bg ~ R ². In panel (b), symbol indicates the radius of the progenitor: triangles— R ⩾ 400 km, squares—300 km ⩽ R < 400 km, diamonds—200 km ⩽ R < 300 km, circles— R ⩽ 200 km.