1. A machine-implemented method comprising: obtaining a plurality of instances and a plurality of attributes, wherein each instance has one or more attributes of the plurality of attributes as attributes of the instance; for each attribute of an instance: identifying a plurality documents from an unstructured document collection that are relevant to the instance, where each of the documents include at least a value for the attribute of the instance; grouping values of the attribute of the instance into two or more groups; and establishing a subset of the one or more values of the attribute as characterizing the instance including selecting one group of values from the two or more groups; and adding each instance, the respective attributes of each instance, and the respective subset of values for the corresponding attributes to a structured data collection.