Table 1

Non-cycloplegic subjective refractions (SR) were independently measured for each eye by 50 experienced optometrists (>5 years)

 Right eye Left eye Means: F (D or m-1) Means: f (D or m-1 ) Means ( ): Clinical notation (D, D, °) Variance–covariance matrices (D2) Volumes (D 3 ) 95% distribution ellipsoids 18.952 1.976 95% confidence ellipsoids 0.064 0.007 Mean excesses Scientific notation (D) –0.0000I+0.0000J – 0.0000K 0.0000I – 0.0000J – 0.0004K Clinical notation (D, D, °) –0.00–0.00×145 0.00–0.00×129 Norms or magnitudes of mean excesses (D) 0.000 0.000
• The sample means are given using three methods, namely, using dioptric power matrices (F)—see Equation 1 above, transposed coordinate vectors (f)—see Equation 5 for the same but as column rather than row vectors, and standard or clinical notation (F s F c A). Variance-covariance matrices and the volumes for 95% surfaces of constant probability density (SCPD), that is, 95% distribution and confidence ellipsoids on means (CEM) are also included. Excesses (see later) of SR and the criterion-standard, either OD or OS as applicable, are also included.