Figure 2.

Test duration—Bland-Altman plots. (a) Example of proportional effect for comparisons to 3°/second stimulus speeds, the dotted lines represent ±1.96 SD of −1.21 to 4.73. The solid line represents the mean bias of 1.76 minutes. There is a proportional effect in which the difference in test duration between the two tests increases as the average test duration of the two tests increases. Thus, the longer the average test, the more difference occurs. (b) Example of close comparisons to 5°/second stimulus speeds, the dotted lines represent ±1.96 SD of −2.36 to 1.63. The solid line represents the mean bias of −0.36 minutes. Most differences lie close to the mean difference and within the limits of agreement.