Figure 5 shows how signed (
Figs. 5a,
5b) and absolute (
Figs. 5c,
5d) differences between best estimates and model predictions related to between-observer variability in best estimates and observers'
conviction in tracing across visual field locations. Locations with greater discordance between the model and observers' best estimates tended to be those with lower observer
conviction and greater between-observer variability in best estimates. Spearman's rank correlation between median range of best estimates and median
conviction was −0.91 for clinicians and −0.93 for naïve observers (both
P < 0.001). Spearman's rank correlation between median
conviction and absolute differences between best estimates and model predictions was −0.35 for clinicians and −0.36 for naïve observers (both
P = 0.01). Spearman's correlation between median range of best estimates, and absolute differences between best estimates and model predictions was 0.42 (
P = 0.002) for clinicians and 0.47 (
P < 0.001) for naïve observers. For locations with larger differences between model-predicted sectors and observers' best estimates, the tendency was for best estimates to be more nasal on the optic nerve head than the model-predicted sectors (
Figs. 5a,
5b). This also can been seen in the most superior and most inferior locations in
Figure 2. The six visual field locations closest to the papillomacular bundle (i.e., the four locations around fixation and the two locations immediately nasal to the blind spot) are marked with an “X” in
Figure 5. These locations exhibited close agreement between the model-predicted sectors and observers best estimates, and observers showed high
conviction and low variability in best estimates at these locations. Several outliers in
Figure 5 are marked with their visual field coordinates, and share common properties of large distance from the optic nerve head, high between-observer variability in best estimates, and low observer
conviction in tracing. In
Figures 5c and
5d, most points lie beneath the line of equality, indicating that the magnitude of differences between the model and best estimates typically was less than the magnitude of between-observer variability in best estimates.