“…As pointed out by one referee, there are several ways, in addition to the CV method, for optimal weight determination in practice, such as the Mallows criterion, 22,48,55 Kullback-Leibler criterion, 27,29,30,56 Jackknife or leave-one-out approach, 47,[57][58][59] and forward-validation technique. [60][61][62] Each method has its own merit and usage scenario.…”