Dichotomous vs. interval rating of headache symptomatology: an investigation in the reliability of headache assessment.
D000328:Adult; D000368:Aged; D005069:Evaluation Studies as Topic; D006261:Headache / Q000175:diagnosis*; D006801:Humans; D008875:Middle Aged; D012107:Research Design / Q000592:standards; D011795:Surveys and Questionnaires