Fig. 1From: Using natural language processing to automatically classify written self-reported narratives by patients with migraine or cluster headacheKey words per diagnosis (red colour migraine, blue colour cluster headache). Legend: (*) = p < 1*10–2, (**) = p < 1*10–5, (***) = p < 1*10–8. Abbreviations: chi2abs = absolute value of the chi-squared statistic, en = English, nl = DutchBack to article page