Table 2.

Headache frequency reported by adolescents retrospectively (last one year) and during three-week prospective diary recordings

Headache frequency (proportion of days)	Interview (n = 310)	Diary (n = 310)	Overall	Post hoc test
	n (%)	n (%)	p-value	p-valuea
≤10 %	252 (81.3)	84 (27.1)	<0.001	<0.001
11–49 %	49 (15.8)	147 (47.4)		<0.001
≥50 %	9 (2.9)	79 (25.5)		<0.001

Only participants who reported having had one type of headache last year in their interview and filled in the diary for ≥1 day are included in the table

^aMcNemar–Bowker test of cell proportion symmetry