Table 2.

Incidence rate ratios and 95% CIs from regression models testing for main effects of gas, condition and rule. Air, self and like are the reference categories.

	Positive responses				Errors to criterion
	Coefficient	95% CI		p	Coefficient	95% CI		p
Gas	0.99	0.95	1.04	0.757	1.33	1.21	1.46	< 0.001
Condition	0.96	0.92	1.01	0.105	1.11	1.01	1.22	0.026
Rule	0.27	0.26	0.29	< 0.001	1.48	1.34	1.63	< 0.001