Table 2.

Comparison between skin ageing phenotypes grades by assessors and participants evaluated using Spearman correlation, Cohen's kappa, and area under the receiver operating characteristic (ROC) curve (AUC)

Category	Phenotype	Test	The self-reported phenotype by the participant is compared against:
			An investigator-administered grading by our assessors (lax definitiona)		An investigator-administered grading by our assessors (moderately-strict definitionb)		An investigator-administered grading by our assessors (strict definitionc)
			Value	p value	Value	p value	Value	p value
Wrinkles	Crow’s Feet wrinkles	Spearman’s rank correlation (ρ)	0.331	4.65 × 10−29	0.281	4.64 × 10−21	0.346	1.04 × 10−31
		Cohen’s kappa (κ)	0.101	9.98 × 10−16	0.180	4.42 × 10−15	0.109	1.00 × 10−11
		Area under curve (AUC) (assessor)d	0.671	1.79 × 10−11	0.798	5.28 × 10−15	0.772	1.09 × 10−11
		Area under curve (AUC) (participant)e	0.722	1.45 × 10−13	0.659	1.16 × 10−7	0.731	1.34 × 10−14
Wrinkles	Forehead wrinkles	Spearman’s rank correlation (ρ)	0.286	3.64 × 10−32	0.348	4.34 × 10−32	0.307	4.90 × 10−25
		Cohen’s kappa (κ)	0.134	6.71 × 10−20	0.233	5.79 × 10−25	0.105	2.75 × 10−12
		Area under curve (AUC) (assessor) d	0.671	3.41 × 10−11	0.828	7.36 × 10−18	0.765	2.60 × 10−13
		Area under curve (AUC) (participant)e	0.692	1.60 × 10−12	0.686	7.01 × 10−12	0.704	5.66 × 10−14
Wrinkles	Glabellar frowns	Spearman’s rank correlation (ρ)	0.273	5.42 × 10−20	0.289	2.92 × 10−22	0.249	9.85 × 10−17
		Cohen’s kappa (κ)	0.170	5.74 × 10−17	0.113	6.98 × 10−16	0.065	6.27 × 10−13
		Area under curve (AUC) (assessor) d	0.795	8.70 × 10−5	0.911	1.21 × 10−7	0.840	5.10 × 10−5
		Area under curve (AUC) (participant)e	0.615	2.09 × 10−3	0.614	2.30 × 10−3	0.601	6.85 × 10−3
Wrinkles	Nasolabial folds	Spearman’s rank correlation (ρ)	0.339	1.55 × 10−30	0.351	1.25 × 10−32	0.366	1.42 × 1035
		Cohen’s kappa (κ)	0.053	9.65 × 10−4	0.190	2.58 × 10−25	0.136	2.07 × 10−13
		Area under curve (AUC) (assessor) d	0.771	3.17 × 10−14	0.847	7.40 × 10−16	0.771	3.17 × 10−14
		Area under curve (AUC) (participant)e	0.839	3.49 × 10−9	0.877	4.75 × 10−11	0.856	5.34 × 10−10
Photo-ageing	Wrinkling constituent of photo-ageing as measured by the Larnier scale	Spearman’s rank correlation (ρ)	0.246	2.24 × 10−16	0.383	4.86 × 10−39	0.329	1.09 × 10−28
		Cohen’s kappa (κ)	0.041	9.80 × 10−5	0.149	5.41 × 10−25	0.181	1.01 × 10−24
		Area under curve (AUC) (assessor) d	0.769	3.00 × 10−6	0.853	7.47 × 10−10	0.769	3.00 × 10−6
		Area under curve (AUC) (participant)e	0.750	5.63 × 10−10	0.806	3.02 × 10−14	0.750	5.63 × 10−10
Photo-ageing	Dyspigmentation constituent of photo-ageing as measured by the Korean scale	Spearman’s rank correlation (ρ)	0.203	1.63 × 10−11	0.278	1.44 × 10−20	0.226	5.54 × 10−14
		Cohen’s kappa (κ)	0.099	1.09 × 10−10	0.155	8.34 × 10−22	0.130	2.28 × 10−12
		Area under curve (AUC) (assessor) d	0.716	6.65 × 10−7	0.727	6.89 × 10−4	0.716	6.65 × 10−7
		Area under curve (AUC) (participant)e	0.683	1.79 × 10−10	0.722	1.18 × 10−14	0.689	4.27 × 10−11

^aLax definition: a phenotype is determined to be present if any of the three assessors identify it

^bModerately strict definition: a phenotype is determined to be present if at least two of the three assessors identify it

^cStrict definition: a phenotype is determined to be present only if all three assessors identify it

^dArea under curve (assessor): area under the receiver operating characteristic (ROC) curve (AUC) when the grading by the assessor is treated as the putative gold standard

^eArea under curve (participant): area under the receiver operating characteristic (ROC) curve (AUC) when the grading by the participant is treated as the putative gold standard