Repeatability Coefficient Limits Of Agreement

The signed-rank Wilcoxon test was used to compare uncorrected IOP and corrected IOP and compare IOP values between NT-530P and GAT. Spearman`s rank correlation coefficient was used to determine correlations between CTC and uncorrected or corrected IOPs. Linear correlations were used to determine the consistency between the CTC and the corrected IOP and the CTC and the uncorrected IOP. Results are expressed on average ± standard deviation (SD) and a value value was considered statistically significant. The distribution of birth weight shows that there are many more low birth weight babies than we would have expected in a representative sample of births. There are 4/65 below 1000 gs. The correlation coefficient is much higher than in a representative sample. If a method has poor repeatability, the agreement between the two methods will also be bad. If both methods have poor repeatability, the agreement will be even worse. If we compare the agreement with an old method with poor repeatability, even a perfect new method will not agree. The average value and SD of the uncorrected IOP purchased by the Examiner (A) was 13.8 ± 2.6 mmHg and the uncorrected IOP purchased by the examiner (B) was 13.9 ± 2.6 mmHg. The average value and CTC SD acquired by the Examiner (A) was 543.3 ± 27.9 m and the CTC acquired by the Examiner (B) was 544.3 ± 27.8 m. The coefficient of variation for unaddrecovered IOPs and CTCs was 6.4% and 0.4%, respectively (Table 1).

The average difference (95% compliance) in the uncorrected IOP was mmHg (range between 2.95 and 2.61 mmHg) (Figure 1). The average difference (95% compliance) in CTC between the two reviewers was nm (range: 9.50 to 7.64 m) (Figure 2). Although it is still not a measure of absolute compliance, the intraclass correlation coefficient (CCI) is often reported in place of the pearson (r). CCI is commonly used to calculate the correlation between more than two sets of measures (usually for more than two physicians completing an assessment on a group of people) [2,10]. In addition, Ogbuehi et al. indicated that there were static differences between IOP values between RKT7000 (Nidek) and GAT (2.6 ± 2.0 mmHg) and between CT-80 (Topcon) and GAT (2.8 ± 2.0 mmHg). The 95% limit of the agreement between GAT and RKT-7700 and between GAT and CT-80 was between 6.5% and 1.3 mmHg and 6.7 to 1.1 mmHg [13]. In this study, there was no significant difference between the iOP values measured with NT-530P and GAT. The average difference (95% agreement compliance) in the IOP between NT-530P and GAT was 0.10 ± 1.97 mmHg (range 3.76 to 3.95 mmHg).