1. a method for adjusting a system for classifying a data item in a document: in a data collection or an element instance within a document; associating with any element instance in the document a set of features indicative of accurate identification of the element instance; providing a training set comprising a subset of elements within the document labeled with class labels; providing a learning method including trained with annotated elements for predicting class labels for unlabeled elements; identifying an element instance within the unlabeled elements including predicting a class of selected element instances; computing a confidence factor that a selected element instance is accurately identified by the predicted class; for a selected element instance having a low confidence factor, querying a human annotator/expert for a true class label of the instance, and; extending the training set with the true labeled instance and iterating the identifying and computing for another element instance with a low confidence factor.