Table 4.

Cross-classification and κ Coefficient of the FFQ-1 and the FFQ-2 Categories^a of Daily Caffeine and Caffeinated Beverage Intakes (n = 224) in the BioCycle Study, 2005–2007

	Same Category		Adjacent Category		Extreme Category		Weighted κ	95% CI
	No.	%	No.	%	No.	%
Caffeine, mg/day	158	71	64	29	0	0	0.76	0.70, 0.81
Coffee, cups/dayb,c	190	85	14	6	0	0	0.88	0.84, 0.92
Coffee drinks/cocoa, cups/dayd	144	64	37	17	4	2	0.56	0.47, 0.64
Tea, cups/day	150	67	40	18	10	4	0.62	0.53, 0.70
Soda, cups/day	155	69	60	42	1	0.004	0.72	0.66, 0.79

Abbreviations: CI, confidence interval; FFQ-1, food frequency questionnaire captured at the end of menstrual cycle 1; FFQ-2, food frequency questionnaire captured at the end of menstrual cycle 2.

^a Caffeine intake is divided into 4 categories on the basis of quartiles; intake of caffeinated beverages is divided into 4 categories: nonconsumers and tertiles.

^b Coffee is all types but “not lattes or mochas.”

^c 1 cup = 237 mL.

^d Coffee drinks/cocoa includes “latte, cappuccino, mocha, or hot chocolate.”