Table 1.

Demographic characteristics of the included sample compared to the excluded sample

Demographic characteristics	Included (% of 402)	Excluded (% of 2599)	Sample comparison
Sex
Male	37.6	41.1	χ2(1) = 1.84
Female	62.4	58.9	P = 0.175
Race
White	66.1	67.4
Black or African American	23.2	25.0
Asian or Pacific Islander	5.1	2.2
Mixed race	2.6	2.1
Native American/American Indian	1.0	1.2
Other	2.0	2.1	P = 0.067a
Ethnicity
Hispanic	15.6	16.7	χ2(1) = 0.31
Not Hispanic	84.4	83.3	P = 0.574
Family income of 2009
Less than 20 000	19.2	29.2
20 000–40 000	20.3	25.4
40 000–75 000	29.7	23.0	χ2(3) = 29.18
75 000 or higher	30.8	22.4	P = 0.000
Education
Not finish high school	5.5	15.7
High school degree	25.3	32.3
Some vocational school or college	29.9	22.8
College degree or higher	38.8	28.6
Do not Know/Refuse	0.5	0.6	P = 0.000a
Age group
18–24 years	30.6	9.1
25–44 years	48.2	24.5
45–64 years	18.4	38.8
65–95 years	2.8	27.5
Do not Know/Refuse	0	0.1	P = 0.000a

^aFisher's exact test was used for variables where at least one cell had an expected frequency of five or less, which violates the assumption of the chi‐square test. Fisher's exact test has no such assumption and thus was used as the appropriate test for these cases. Fisher's exact test does not have a test statistic and only yields the P‐value.