Comparing the spread of accuracies
within each action (class)for the KTH dataset in Table 3,it is clear that the 3d-SIFT descriptor has the lowest range (97%-87%=10%)follwed by the 3d-HOG descriptor (96%-84%=12%).The spread of accuracies for other reported work ranges from 13%to 45%.A similar smllest spread can be seen for the SIFT-NBNN combination from Table 8 for the IXMAS dataset.