TABLE 4.

Random forest ranking of proteins included in the final salivary IgG assay

SARS-CoV-2 protein	Protein IDa	Gini coefficient	Gini_OOBb	Parsimonious model
Spike	EPA_S	0.352	0.312	Yes
Spike	AB_S	0.037	0.024	No
Nucleocapsid	AB_N	0.012	0.002	Yes
Spike stalk subunit	PS_S2i	0.012	0.001	Yes
Receptor binding domain	EPA_RBD	0.007	0.000	Yes
Spike	RD_S	0.009	−0.005	No
Receptor binding domain	AB_RBD	0.018	−0.006	No
Spike globular subunit	CD_S1	0.009	−0.007	No
Nucleocapsid	RD_N	0.011	−0.009	No
Receptor binding domain	SB_RBDn	0.025	−0.016	No

^aProtein IDs are defined in Results and Table 2.

^bOOB, out-of-box.