Fig. 1

Study participant flow chart
1 Targeted sampling to represent the Japanese adult population in terms of key demographic characteristics (age, sex, and geography) was applied. 2 This included those who passed the screener stage and represented the Japanese census adult population. 3 A quota of 2000 was set for the non-migraine group, and about 2000 respondents were selected from the eligible population while preserving its demographic composition. The majority of respondents eligible for this group were over quota. Abbreviations: CM – Chronic Migraine, N – Total population size, n – Sample size, OTC – Over-the-counter