Table 4. The correlations among the 6 FTND items.

correlation	ftnd_2	ftnd_3	ftnd_4	ftnd_5	ftnd_6
ftnd_1	0.6815	0.6758	0.7528	0.6446	0.7770
ftnd_2		0.4579	0.5895	0.4403	0.6838
ftnd_3			0.4822	0.6394	0.5294
ftnd_4				0.4452	0.6702
ftnd_5					0.5110