Average probability of detection (POD) as a function of range.

<p>Each scatter point refers to a distinct distance class of one of the transects and its corresponding subset of visual observations from , drawn on the horizontal axis at its mean range. The modelled POD equals the mean GAM prediction for these observations. The observed POD equals the proportion of these observations that could be matched to a radar track directly. Lines indicate the upper and lower 1 confidence intervals.