TABLE 3.

Significant associations between coal chemistry and the cell response identified using stepwise multiple regression. Multivariate linear regression was applied to determine whether these associations were maintained after adjustment for particle size

	Stepwise regression analysis				Linear regression analysis
Cell response	R2 change	β	ANOVA (F)	p	β	95% CI	p
PC1
K2O	0.628	0.792	28.678	<0.0001	0.821	0.489–1.154	<0.0001
PC2
Fe2O3	0.235	−0.588	5.673	0.014	−0.427	−0.739 – −0.116	0.011
P2O5	0.180	−0.436			−4.622	−10.260 – 1.116	0.107
PC3	—	—	—	—	—	—	—

Abbreviation: PC, principal component.