Table 2.

Signal quality indices comparison of the annotators and the adjudicator ranked in ascending order based on the p value.

Annotator 1
G1 versus G2				G1 versus (G2 & G3)				G1 versus G3
Index	G1 ($\mathit{n}=\mathbf{33}$)	G2 ($\mathit{n}=\mathbf{26}$)	$\mathit{p}$ Value	Index	G1 ($\mathit{n}=\mathbf{33}$)	G2 & G3 ($\mathit{n}=\mathbf{73}$)	$\mathit{p}$ Value	Index	G1 ($\mathit{n}=\mathbf{33}$ )	G3 ($\mathit{n}=\mathbf{47}$)	$\mathit{p}$ Value
${\mathrm{S}}_{\mathrm{SQI}}$	0.07 ± 0.20	−0.07 ± 0.19	3.8 $\times {10}^{-3}$**,†	${\mathrm{S}}_{\mathrm{SQI}}$	0.07 ± 0.20	−0.14 ± 0.18	1.0 $\times {10}^{-6}$**,†	${\mathrm{S}}_{\mathrm{SQI}}$	0.07 ± 0.20	−0.18 ± 0.17	2.78 $\times {10}^{-7}$**,†
${\mathrm{R}}_{\mathrm{SQI}}$	0.88 ± 0.10	0.91 ± 0.07	$0.048$ *	${\mathrm{M}}_{\mathrm{SQI}}$	95.45 ± 8.99	66.69 ± 41.35	2.57 $\times {10}^{-5}$**,†	${\mathrm{M}}_{\mathrm{SQI}}$	95.45 ± 8.99	57.39 ± 43.19	2.90 $\times {10}^{-7}$**,†
${\mathrm{N}}_{\mathrm{SQI}}$	57.60 ± 3.76	57.11 ± 6.42	0.072	${\mathrm{Z}}_{\mathrm{SQI}}$	61.13 ± 2.62	67.45 ± 11.89	$0.001$ **	${\mathrm{Z}}_{\mathrm{SQI}}$	61.13 ± 2.62	70.15 ± 13.50	2.12 $\times {10}^{-5}$**,†
${\mathrm{E}}_{\mathrm{SQI}}$	4.82 ± 0.56	4.96 ± 1.10	0.073	${\mathrm{P}}_{\mathrm{SQI}}$	91.24 ± 6.61	86.40 ± 9.05	$0.01$ *,†	${\mathrm{P}}_{\mathrm{SQI}}$	91.24 ± 6.61	84.17 ± 9.17	5.96 $\times {10}^{-4}$**,†
${\mathrm{K}}_{\mathrm{SQI}}$	2.05 ± 0.16	2.01 ± 0.16	0.147	${\mathrm{K}}_{\mathrm{SQI}}$	2.05 ± 0.16	2.01 ± 0.14	0.14	${\mathrm{K}}_{\mathrm{SQI}}$	2.05 ± 0.16	2.01 ± 0.13	0.24
${\mathrm{M}}_{\mathrm{SQI}}$	95.45 ± 8.99	83.50 ± 32.18	0.161	${\mathrm{N}}_{\mathrm{SQI}}$	57.60 ± 3.76	61.51 ± 13.90	0.34	${\mathrm{E}}_{\mathrm{SQI}}$	4.82 ± 0.56	3.77 ± 2.18	0.39
${\mathrm{Z}}_{\mathrm{SQI}}$	61.13 ± 2.62	62.59 ± 5.82	0.436	${\mathrm{R}}_{\mathrm{SQI}}$	0.88 ± 0.10	0.82 ± 0.23	0.45	${\mathrm{N}}_{\mathrm{SQI}}$	57.60 ± 3.76	63.95 ± 16.22	0.84
${\mathrm{P}}_{\mathrm{SQI}}$	91.24 ± 6.61	90.42 ± 7.43	0.485	${\mathrm{E}}_{\mathrm{SQI}}$	4.82 ± 0.56	4.19 ± 1.95	0.85	${\mathrm{R}}_{\mathrm{SQI}}$	0.88 ± 0.10	0.78 ± 0.28	0.86
Annotator 2
G1 versus G2				G1 versus (G2 & G3)				G1 versus G3
Index	G1 ($\mathit{n}=\mathbf{44}$)	G2 ($\mathit{n}=\mathbf{21}$)	$\mathit{p}$ Value	Index	G1 ($\mathit{n}=\mathbf{44}$)	G2 & G3 ($\mathit{n}=\mathbf{62}$)	$\mathit{p}$ Value	Index	G1 ($\mathit{n}=\mathbf{44}$)	G3 ( $\mathit{n}=\mathbf{41}$)	$\mathit{p}$ Value
${\mathrm{S}}_{\mathrm{SQI}}$	0.07 ± 0.18	−0.10 ± 0.20	1.9 $\times {10}^{-3}$**,†	${\mathrm{S}}_{\mathrm{SQI}}$	0.07 ± 0.18	−0.17 ± 0.17	3.4 $\times {10}^{-9}$**,†	${\mathrm{S}}_{\mathrm{SQI}}$	0.07 ± 0.18	−0.21 ± 0.14	7.4 $\times {10}^{-10}$**,†
${\mathrm{M}}_{\mathrm{SQI}}$	91.73 ± 21.62	65.66 ± 42.88	$0.006$ *,†	${\mathrm{M}}_{\mathrm{SQI}}$	91.73 ± 21.62	64.22 ± 41.48	4.9 $\times {10}^{-6}$**,†	${\mathrm{Z}}_{\mathrm{SQI}}$	61.82 ± 5.87	69.58 ± 12.46	9.5 $\times {10}^{-8}$**,†
${\mathrm{N}}_{\mathrm{SQI}}$	58.23 ± 6.34	59.86 ± 12.22	0.121	${\mathrm{Z}}_{\mathrm{SQI}}$	61.82 ± 5.87	68.09 ± 12.02	3.1 $\times {10}^{-5}$**,†	${\mathrm{M}}_{\mathrm{SQI}}$	91.73 ± 21.62	63.49 ± 41.26	5.2 $\times {10}^{-6}$**,†
${\mathrm{K}}_{\mathrm{SQI}}$	2.05 ± 0.17	1.97 ± 0.10	0.123	${\mathrm{P}}_{\mathrm{SQI}}$	89.93 ± 7.81	86.47 ± 8.96	$0.04$ *	${\mathrm{P}}_{\mathrm{SQI}}$	89.93 ± 7.81	85.98 ± 9.70	$0.04$ *
${\mathrm{P}}_{\mathrm{SQI}}$	89.93 ± 7.81	87.43 ± 7.44	0.176	${\mathrm{N}}_{\mathrm{SQI}}$	58.23 ± 6.34	61.76 ± 14.41	0.29	${\mathrm{E}}_{\mathrm{SQI}}$	4.77 ± 0.92	4.03 ± 2.04	0.56
${\mathrm{R}}_{\mathrm{SQI}}$	0.87 ± 0.13	0.85 ± 0.22	0.182	${\mathrm{K}}_{\mathrm{SQI}}$	2.05 ± 0.17	2.01 ± 0.12	0.48	${\mathrm{N}}_{\mathrm{SQI}}$	58.23 ± 6.34	62.73 ± 15.47	0.64
${\mathrm{Z}}_{\mathrm{SQI}}$	61.82 ± 5.87	65.18 ± 10.82	0.546	${\mathrm{E}}_{\mathrm{SQI}}$	4.77 ± 0.92	4.12 ± 2.00	0.70	${\mathrm{R}}_{\mathrm{SQI}}$	0.87 ± 0.13	0.80 ± 0.25	0.73
${\mathrm{E}}_{\mathrm{SQI}}$	4.77 ± 0.92	4.30 ± 1.95	0.933	${\mathrm{R}}_{\mathrm{SQI}}$	0.87 ± 0.13	0.82 ± 0.24	0.72	${\mathrm{K}}_{\mathrm{SQI}}$	2.05 ± 0.17	2.03 ± 0.13	1.00
Adjudicator
G1 versus G2				G1 versus (G2 & G3)				G1 versus G3
Index	G1 ($\mathit{n}=\mathbf{36}$)	G2 ($\mathit{n}=\mathbf{52}$ )	$\mathit{p}$ Value	Index	G1 ($\mathit{n}=\mathbf{36}$)	G2 & G3 ($\mathit{n}=\mathbf{70}$)	$\mathit{p}$ Value	Index	G1 ($\mathit{n}=\mathbf{36}$)	G3 ($\mathit{n}=\mathbf{18}$)	$\mathit{p}$ Value
${\mathrm{S}}_{\mathrm{SQI}}$	0.11 ± 0.17	−0.17 ± 0.14	3.3 $\times {10}^{-10}$**,†	${\mathrm{S}}_{\mathrm{SQI}}$	0.11 ± 0.17	−0.17 ± 0.17	6.3 $\times {10}^{-11}$**,†	${\mathrm{S}}_{\mathrm{SQI}}$	0.11 ± 0.17	−0.16 ± 0.23	1.1 $\times {10}^{-5}$**,†
${\mathrm{N}}_{\mathrm{SQI}}$	60.07 ± 7.69	59.40 ± 13.35	$0.001$**,†	${\mathrm{M}}_{\mathrm{SQI}}$	84.26 ± 31.62	71.21 ± 39.10	0.01 *	${\mathrm{Z}}_{\mathrm{SQI}}$	63.20 ± 7.95	69.97 ± 11.69	1.4 $\times {10}^{-4}$**,†
${\mathrm{K}}_{\mathrm{SQI}}$	2.06 ± 0.16	1.97 ± 0.08	0.005 *,†	${\mathrm{Z}}_{\mathrm{SQI}}$	63.20 ± 7.95	66.66 ± 11.30	0.01 *	${\mathrm{M}}_{\mathrm{SQI}}$	84.26 ± 31.62	64.04 ± 42.07	1.3 $\times {10}^{-3}$**,†
${\mathrm{R}}_{\mathrm{SQI}}$	0.85 ± 0.14	0.86 ± 0.23	0.016 *	${\mathrm{N}}_{\mathrm{SQI}}$	60.07 ± 7.69	60.41 ± 13.54	0.01 *	${\mathrm{K}}_{\mathrm{SQI}}$	2.06 ± 0.16	2.14 ± 0.17	0.05
${\mathrm{E}}_{\mathrm{SQI}}$	4.39 ± 1.20	4.60 ± 1.82	0.021 *	${\mathrm{E}}_{\mathrm{SQI}}$	4.39 ± 1.20	4.39 ± 1.87	0.13	${\mathrm{R}}_{\mathrm{SQI}}$	0.85 ± 0.14	0.76 ± 0.24	0.20
${\mathrm{M}}_{\mathrm{SQI}}$	84.26 ± 31.62	73.69 ± 38.13	0.049 *	${\mathrm{K}}_{\mathrm{SQI}}$	2.06 ± 0.16	2.01 ± 0.13	0.14	${\mathrm{P}}_{\mathrm{SQI}}$	88.89 ± 7.81	84.22 ± 10.98	0.23
${\mathrm{Z}}_{\mathrm{SQI}}$	63.20 ± 7.95	65.52 ± 11.05	0.115	${\mathrm{R}}_{\mathrm{SQI}}$	0.85 ± 0.14	0.83 ± 0.23	0.16	${\mathrm{E}}_{\mathrm{SQI}}$	4.39 ± 1.20	3.77 ± 1.91	0.40
${\mathrm{P}}_{\mathrm{SQI}}$	88.89 ± 7.81	88.50 ± 8.10	0.557	${\mathrm{P}}_{\mathrm{SQI}}$	88.89 ± 7.81	87.40 ± 9.04	0.37	${\mathrm{N}}_{\mathrm{SQI}}$	60.07 ± 7.69	63.32 ± 14.05	0.88

Mean and standard deviation values of signal quality indices: perfusion (${\mathrm{P}}_{\mathrm{SQI}}$), kurtosis (${\mathrm{K}}_{\mathrm{SQI}}$), skewness (${\mathrm{S}}_{\mathrm{SQI}}$), relative power (${\mathrm{R}}_{\mathrm{SQI}}$), non-stationarity (${\mathrm{N}}_{\mathrm{SQI}}$), zero crossing (${\mathrm{Z}}_{\mathrm{SQI}}$), entropy (${\mathrm{E}}_{\mathrm{SQI}}$), and matching of systolic wave detectors (${\mathrm{M}}_{\mathrm{SQI}}$). The p-value of discriminating between excellent signal quality (G1), acceptable quality (G2), and unfit to diagnose signals (G3) is given in the last column of each comparison. Uncorrected p-values from the Mann–Whitney test, where * and ** indicate $p<0.05$ and $p<0.005$, respectively; ^† indicate p-values that remain significant after post-correction (Bonferroni-Holm, $\alpha <0.05$).