Table 1.

Percent of respondents using different explanations for their probability judgments, in overall sample, and by probability judgment, education and numeracy.

		Percent using “good estimate” explanation		Percent using “don’t know” explanation		Chi-square test comparing use of explanations
	N	Not quite sure	Don’t like to think about it	No idea	No one can know	All four	“Good estimate” vs. “Don’t know”
Overall sample	1020	16.5%	20.2%	11.6%	51.8%	-	-
Probability judgment
50%	173	6.4%	12.7%	13.9%	67.1%	χ(3)=29.07	χ(1)=27.76
Other	847	18.5%	21.7%	11.1%	48.6%	p<.001	p<.001
Education †
No college degree	676	11.8%	19.5%	10.1%	58.6%	χ(3)=54.80	χ(1)=30.40
College degree	292	27.7%	22.3%	14.0%	36.0%	p<.001	p<.001
Numeracy ‡
Low numeracy	585	11.3%	19.0%	12.1%	57.6%	χ(3)=32.86	χ(1)=24.27
High numeracy	435	23.4%	21.8%	10.8%	43.9%	p<.001	p<.001

^†A total of 968 respondents reported whether or not they had a college education.

^‡Numeracy groups were split by their median (=.73). Mean numeracy differed significantly across the four respective explanations (M=.75, SD=.22 vs. M=.69, SD=.24 vs. M=.66, SD=.23, vs. M=.63, SD=.25), F(3, 1016)=9.95, p<.001, as well as their “good estimate” (M=.71, SD=.23) vs. “don’t know” (M=.64, SD=.25), t(1018)=4.73, p<.001.