. 2012 May 11;7(5):e36820. doi: 10.1371/journal.pone.0036820

Table 1. Demographic characteristics of non-users, experimenters, and chronic users.

	Non-Users (N = 48)	Experimenters (N = 48)	Chronic Users (N = 48)
Age	19.71 (2.59)	20.75 (2.78)	20.42 (2.52)	F (2,141) = 1.96, p = .14
Years of University	1.94 (1.24)^a	2.71 (1.22)^b	2.22 (1.06)^a	F (2,141) = 5.25, p = .006
Estimated Verbal IQ	99.00 (9.13)^a	103.63 (8.16)^b	105.86 (7.41)^b	F (2,141) = 8.61, p<.001
% Female	79.17%^a	60.42%^b	47.92%^b	χ² (2) = 8.01, p = .02
% English First Language	45.83%^a	70.83%^a	81.25%^b	χ² (2) = 14.17, p = .001

Note: bold indicates p≤05. Verbal IQ was estimated using the NAART and the following equation, 128.7−.89 x NAART Errors. Groups with different subscripts differed significantly.