. 2017 Nov 27;12(11):e0188638. doi: 10.1371/journal.pone.0188638

Table 2. Eigenvectors in support of respirator fit test panels of principal component analysis design developed from this study, by the U.S.

National Institute for Occupational Safety and Health (NIOSH), and by Chen et al.

Head-and-face dimension ^a	First principal component			Second principal component
Head-and-face dimension ^a	This study	NIOSH	Chen et al.	This study	NIOSH	Chen et al.
Head breadth	0.641031	0.372241	0.373045	0.032379	0.013306	−0.132683
Minimum frontal breadth	0.555771	0.343264	0.322260	−0.434911	−0.152951	−0.388836
Interpupillary distance	0.766379	0.363474	0.370307	−0.309213	−0.173099	−0.159748
Bizygomatic breadth (face width)	0.665253	0.426498	0.422051	−0.084469	−0.039087	−0.140757
Menton-sellion length (face length)	0.644739	0.329648	0.244826	0.526096	0.359799	0.568632
Bigonial breadth	0.513814	0.372717	0.328562	−0.060759	−0.093279	−0.227790
Nasal root breadth	0.569534	0.202311	0.159204	−0.294401	−0.341235	−0.173192
Nose breadth	0.712228	0.301125	0.321181	−0.071652	−0.210833	0.079405
Subnasale-sellion length (nose length)	0.426506	0.193650	0.297905	0.724967	0.584261	0.528574
Nose protrusion	0.469558	0.113578	0.237882	0.246291	0.551842	0.308739

^a Head-and-face dimensions reported by the NIOSH were described in Zhuang et al. [11] for subjects of an age distribution from 18 to 65 years old; those reported by Chen et al. [17] were for subjects from 18 to 66 years old.