Fig 8. Distribution of normative Randot Preschool stereo thresholds in different age-groups, for children with normal vision, separated by sex.

In children aged 4 and up, the most common outcome is 40 arcsec, the best score available. Dots show the fit of a descriptive model fitted to this data (Eq 1). For each child in the study, given their age and sex, the model estimated the probability of each possible score. We then averaged these across all children of a given sex and age-group to obtain the points shown. With 8 parameters fitted to the data, the model gives a reasonable account of the data in these 84 bins.