Training, test and validation performance.

Given are the training, test and validation performance as measured by Sensitivity (SE) and Positive Predictive Value (PPV). The training and test performances are computed with a 4-fold cross validation on the training set. In the validation step, iSIS was applied to the entire images for taxa detection and the detection results were compared to our gold standard by computing SE and PPV. The performance decreases significantly from the test data to the validation due to an increase in FP. The last row shows SE and PPV results after a careful re-evaluation of the FP (see text for details) yielding our final estimates for iSIS’ SE and PPV. The last column shows the correlation between object counts of the gold standard items and the machine detection result for the full transect.