UCINET

UCINET is a Windows software package for social network analysis, developed by Steve Borgatti, Martin Everett, and Lin Freeman and distributed by Analytic Technologies. The canonical release, UCINET 6, is cited to 2002 and has been continuously maintained since; it is now offered as free software requiring no registration code. The name abbreviates "University of California, Irvine NETwork," reflecting its origins in Freeman's work there. It is one of the oldest and most widely cited tools in the SNA field, and its bundled companion NetDraw handles interactive visualization while UCINET itself concentrates on computation.

At its core UCINET treats network data as matrices. A relation is stored as a sociomatrix (a square adjacency matrix whose rows and columns share the same node labels), and multi-relational data as a stack of such matrices. Because everything reduces to matrices, the program exposes a large library of matrix algebra and transformation operations (transpose, multiplication, normalization, dichotomization, aggregation) alongside network-specific procedures. Its analytic breadth is a defining strength: centrality (degree, betweenness, closeness, eigenvector, Bonacich power, and others), cohesive subgroups and cliques, components and k-cores, structural and regular equivalence, blockmodeling and role/position analysis, ego-network measures, two-mode (affiliation) analysis, and permutation-based statistics such as QAP correlation and regression.

Data interchange is built around the DL (Data Language) text format, a self-describing plain-text file that begins with the keyword dl, declares dimensions (rows, columns, matrices), and carries node labels: and a data: block. DL supports several layouts including fullmatrix, edgelist1, and nodelist1, so the same network can be expressed as a dense matrix or a sparse list of ties. UCINET also imports and exports Pajek files (Pajek), reads Excel and raw text, and interoperates with NetDraw's VNA and DL layout formats (Netdraw VNA). This makes it a common bridge to and from tools like Pajek, Gephi, NetDraw, and SocNetV in an analyst's workflow.

The main limitations are platform and scale. UCINET is Windows-only (runnable elsewhere only through emulation) and closed-source, and although it can theoretically address up to two million nodes, its matrix-oriented, largely in-memory design makes it best suited to networks up to roughly ten thousand nodes; very large graphs are better handled by tools such as igraph, NetworkX, or graph-tool. It is a GUI-driven desktop application rather than a scriptable library, which limits automation and reproducible pipelines compared with code-based alternatives.