Fig. 4From: Psychiatric disorders and headache familial recurrence: a study on 200 children and their parentsPsychiatric disorders in parents ×frequency. Percentage count for observed frequencies in psychiatric disorders in parents × frequency (1–3/month = 1; 1/week = 2; >4/month = 3) interaction. Partial χ2 = 6.94; df = 2; P = 0.05. Percentages are calculated separately for each groupBack to article page