Table 1.

Correlation analysis between 6 IrisPlex SNPs, gender and eye colour

Variable	Gene	N	Correlation analysis
			Blue/green/hazel/brown eye colour			Blue/non-blue eye colour
			Correlation coefficienta	Effect sizeb	Pearson p value	Correlation coefficienta	Effect sizeb	Pearson p value
rs12913832	HERC2	1020	0.566/0.766	Large	5.711 × 10−138	0.698/0.810	Large	1.189 × 10−108
rs1800407	OCA2	1020	0.108/0.185	Small	5.508 × 10−4	0.131/0.184	Small	1.539 × 10−4
rs12896399	SLC24A4	1020	0.084/0.145	Small	0.024	0.112/0.157	Small	0.002
rs16891982	SLC45A2	1020	0.089/0.152	Small	0.014	0.085/0.120	Small	0.026
rs1393350	TYR	1020	0.045/0.079	None	0.649	0.044/0.063	None	0.368
rs12203592	IRF4	1020	0.036/0.061	None	0.861	0.023/0.032	None	0.770
Gender	–	1017	0.105/0.148	Small	0.010	0.097/0.137	Small	0.002

^aCorrelation coefficients: Cramér’s V coefficient/adjusted contingency coefficient

^bEffect size: none—k x Cramér’s V coefficient <0.1, small—k x Cramér’s V coefficient 0.1–0.3, medium—k x Cramér’s V coefficient 0.3–0.5, large—k x Cramér’s V coefficient >0.5, where k x Cramér’s V coefficient is so called Cohen’s coefficient and k is equal to the square root of 2 for blue/green/hazel/brown eye colour and all genes and 1 in other cases [17]