Table 2 .

Results of ANCOVA and post hoc pairwise analyses for the four outcome variables

	ANCOVA		Post hoc contrast by estimate marginal means
	$F$	$p$	Group	$t$	$p$
Mean daily counts	6.42	.002	CTL-AO	2.67	.02
			CTL-AP	3.12	.006
			AO-AP	0.62	.54
Mean daily % time > 15,000 counts	7.72	<.001	CTL-AO	2.85	.009
			CTL-AP	3.48	.002
			AO-AP	0.80	.424
Mean daily particle events	4.04	.02	CTL-AO	1.62	.21
			CTL-AP	2.73	.02
			AO-AP	1.13	.26
Air nicotine	1.53	.22	CTL-AO	1.11	.54
			CTL-AP	1.63	.32
			AO-AP	0.51	.61

Bold font indicates p < .05.

AO aversive only contingency; AP aversive plus punishment contingency.