44. A system comprising: a device; and one or more computers programmed to interact with the device and to perform operations comprising: receiving a first instance identifier identifying a first instance that is characterized by first data in a structured data collection organized in accordance with a defined data model, a second instance identifier identifying a second instance that is characterized by second data in the structured data collection, and a first attribute identifier identifying a first attribute of the first and second instances; using the first attribute identifier and the first instance identifier to identify and extract a first collection of values of the first attribute of the first instance from two or more documents of an unstructured electronic document collection; using the first attribute identifier and the first instance identifier to identify and extract a second collection of values of the first attribute of the second instance from two or more documents of the unstructured electronic document collection; selecting a first subset of the first collection of values from amongst the values in the first collection of values as suitably characterizing the first attribute of the first instance; selecting a second subset of the second collection of values from amongst the values in the second collection of values as suitably characterizing the first attribute of the second instance; merging a first value of the first subset and a second value of the second subset into the structured data collection after and in response to the first subset and the second subset being selected as suitably characterizing the first attribute; generating machine-readable instructions for displaying a structured presentation including the first value and the second value, wherein the structured presentation denotes characterization of attributes of particular instances by values that characterize the attributes of the particular instances by virtue of an arrangement of identifiers of the particular instances and the values; and sending the machine-readable instructions to the device.
44. A system comprising: a device; and one or more computers programmed to interact with the device and to perform operations comprising: receiving a first instance identifier identifying a first instance that is characterized by first data in a structured data collection organized in accordance with a defined data model, a second instance identifier identifying a second instance that is characterized by second data in the structured data collection, and a first attribute identifier identifying a first attribute of the first and second instances; using the first attribute identifier and the first instance identifier to identify and extract a first collection of values of the first attribute of the first instance from two or more documents of an unstructured electronic document collection; using the first attribute identifier and the first instance identifier to identify and extract a second collection of values of the first attribute of the second instance from two or more documents of the unstructured electronic document collection; selecting a first subset of the first collection of values from amongst the values in the first collection of values as suitably characterizing the first attribute of the first instance; selecting a second subset of the second collection of values from amongst the values in the second collection of values as suitably characterizing the first attribute of the second instance; merging a first value of the first subset and a second value of the second subset into the structured data collection after and in response to the first subset and the second subset being selected as suitably characterizing the first attribute; generating machine-readable instructions for displaying a structured presentation including the first value and the second value, wherein the structured presentation denotes characterization of attributes of particular instances by values that characterize the attributes of the particular instances by virtue of an arrangement of identifiers of the particular instances and the values; and sending the machine-readable instructions to the device. 45. The system of claim 44 , wherein selecting the first subset of values as suitable comprises: grouping the values in the first collection into groups, wherein each group includes a subset of the first collection of values; determining a confidence that the values in each group accurately characterize the first attribute of the first instance; and ordering the groups in accordance with the respective confidences.