Table 1.

Test-Retest Variability of Domain Scores (θ)

Domain (θ)	Number of Questions	Initial Measurement			Test-Retest (95% CI) (n = 18)
		n	Mean	SD	ρ Correlation	Mean Change	SD ME
Michigan Retinal Degeneration Questionnaire (MRDQ)
Central Vision	11	91	−0.06	0.84	0.83 (0.59, 0.93)	−0.13 (−0.27, 0.02)	0.20 (0.13, 0.28)
Color Vision	4	91	0.02	1.01	0.74 (0.41, 0.90)	0.02 (−0.22, 0.26)	0.34 (0.21, 0.47)
Contrast Sensitivity	7	91	−0.06	0.90	0.75 (0.43, 0.90)	−0.17 (−0.38, 0.03)	0.29 (0.15, 0.43)
Scotopic Function	12	90	−0.04	0.87	0.84 (0.62, 0.94)	−0.05 (−0.25, 0.15)	0.29 (0.20, 0.38)
Photopic Peripheral Vision	9	90	0.03	0.83	0.83 (0.58, 0.93)	−0.16 (−0.33, 0.01)	0.24 (0.16, 0.33)
Mesopic Peripheral Vision	9	90	−0.15	0.81	0.73 (0.40, 0.89)	−0.05 (−0.27, 0.18)	0.32 (0.22, 0.42)
Photosensitivity	7	90	−0.22	0.98	0.82 (0.57, 0.93)	−0.04 (−0.24, 0.16)	0.29 (0.15, 0.43)
Michigan Vision-Related Anxiety Questionnaire (MVAQ)
Rod Function Anxiety	6	89	0.02	0.58	0.78 (0.50, 0.92)	0.04 (−0.18, 0.26)	0.31 (0.13, 0.50)
Cone Function Anxiety	8	90	0.17	0.81	0.86 (0.67, 0.95)	−0.19 (−0.36, −0.02)	0.24 (0.13, 0.36)

95% CI = 95% confidence interval; ρ Correlation = Pearson correlation coefficient; SD ME = standard deviation of measurement error.

Three test-retest statistics (Pearson correlation, mean difference, and standard deviation of measurement error) and their 95% confidence intervals were computed from 18 pairs of tests taken approximately 2 weeks apart).