Table 1.

Percentage of respondents who chose the web-based survey format, overall and by case/control status, and associations between the choice of survey mode (web vs. telephone-administered) and participant characteristics

		Total Cases Choosing Web	Total Controls Choosing Web	Total Participants Choosing Web
Characteristic	No.			%	p value^
Case-control status		209	330
Case	209	--	--	83
Sibling control	153	--	--	90
Friend control	177	--	--	88
P-value*		--	--	0.15	--
Age
<40	143	95	96	96
40–49	125	84	88	86
50–59	159	77	89	85
60+	107	67	80	76
P-value*		0.002	0.02	0.0001	0.79
Gender
Male	267	84	92	88
Female	275	82	86	84
P-value*		0.67	0.09	0.19	0.37
Race/ethnicity
White	517	85	89	87
NonWhite	16	82	100	88
P-value*		0.81	0.43	0.97	0.97
College educated
No	74	61	72	68
Yes	465	87	91	89
P-value*		0.0006	0.0003	0.0001	0.94
Household Income
<25,000	35	75	53	63
25–50,000	72	73	88	83
50–75,000	103	73	89	86
75–100,000	90	79	94	88
>100,000	229	90	92	91
P-value*		0.24	<0.0001	0.0002	0.16
Have an email account
No	49	55	59	57
Yes	490	86	91	89
P-value*		0.0005	<0.0001	0.0001	0.52
Check email daily
Daily	315	92	93	93
Few time a week	111	83	90	87
Weekly	46	81	90	87
Less/Never	18	44	69	44
P-value*		<0.0001	0.02	0.0001	0.87
Use the internet daily
Daily	204	91	96	94
Few time a week	160	88	91	89
Weekly	71	86	95	92
Less/Never	104	60	64	63
P-value*		<0.0001	<0.0001	0.0001	0.57

^*p-value for the chi-square test of the association between survey choice and characteristics, among cases only, controls only, and overall

^{^}p-value for the interaction term between case/control status and the characteristic, from a logistic regression model predicting survey mode