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Tablet-based data-collection software, and related analytic methodologies, aimed at the discovery of whole network topologies, while providing participant confidentiality, and despite participants’ possibly incomplete knowledge of other network members’ identities. This method, called Social Network Analysis via Perceptual Tomography (SNAPT) builds on matching techniques of “propitious aggregation” in network data collection, and “multiple perspective” techniques from semantic link analysis.



The SNAPT platform allows for the collection of network link data by using “selfie” pictures (self-portraits created with a digital camera, or other recognizable images, see below) of respondents who enroll in the project that are shown on a large touch-screen tablet to other SNAPT participants who use “drag and drop” techniques to sort other respondents into “associates/friends”, “recognized” and “unrecognized” bins. To do this, respondents need not know the full identity of those whose images they sort. SNAPT_appThose in the “associates/friends” bin are then reshown after the initial sorting, and the respondent is asked to assign relational qualities to them (e.g. “I would lend him/her money”, “He/she would lend me money”, etc.) Network member sorts by salient roles arranged by the participant are used  to generate network topology data directly from the screen.






SNAPT server


The SNAPT server continuously receives image data from SNAPT tablet(s), and receives sorting data every 24 hours. This includes data on: each participant’s classification of other participants into “associates/friends”, “recognized” and “unrecognized” bins, with “associates/friends” being further categorized.

Anonymity. Participants who provide informed consent to participate will enter their particpant ID into the SNAPT tablet prior to beginning the picture sorting task.  Note that privacy is ensured because all data is indexed by participant ID, and no record binds data to real-world participant identities.  Once aggregated at the SNAPT server, this de-identified sorting data is analyzed to produce a social network with categorically labeled edges.

Confidentiality.  All sorting data stored on the tablet is encrypted by a cryptographic secret key, and once this data has been transferred to the SNAPT server, the transferred data is deleted from the tablet.  The SNAPT server runs on a dedicated machine, residing behind a secure gateway configured to allow transfers of data into the server from authorized tablets, but no possibility of any data transfers out of the server.

Analytic engine


A specialized analytic engine is provided with SNAPT.  This engine is capable of analyzing the sorting data collected by SNAPT, generating a social network, with categorical attributes for each of the directed network links.  The engine outputs the data in standard Pajek format for social network analysis.