Table 3. Results of Deming regression analysis to investigate for proportional, as well as systematic bias between ETDRS chart and crowded Kay Picture acuity measurements.

Model	Deming regression slope (SE)	95% CI slope	95% CI y intercept when x=0
Mean ETDRS acuity (x), mean pCKP (y) (adults)	1.04 (0.06)	0.91, 1.17	−0.17, −0.04
Mean ETDRS acuity (x), mean cCKP (y) (adults)	1.05 (0.08)	0.89, 1.21	−0.22, −0.06
Mean ETDRS acuity (x), mean pCKP (y) (paediatric amblyopes)	0.97 (0.06)	0.85, 1.09	−0.27, −0.14
Mean ETDRS acuity (x), mean cCKP (y) (paediatric amblyopes)	0.95 (0.06)	0.83, 1.06	−0.26, −0.13

In each case, the mean of the test and retest measurements with each technique has been employed.