Document Type
Software
Publication Date
2021
Subjects
Reconstructability Analysis, OCCAM Software, Information Theory, Probabilistic graphical modeling, Multivariate Analysis, Discrete Multivariate Modeling, Data Mining
Abstract
OCCAM is a Discrete Multivariate Modeling (DMM) tool based on the methodology of Reconstructability Analysis (RA). As an acronym it stands for Organizational Complexity Computation and Modeling, and the name is also a reference (with a non-standard spelling) to Ockham’s Razor. The principal programmers of its current version have been Kenneth Willett, Joe Fusion, and Heather Alexander. Ken Willett totally rewrote earlier versions of OCCAM. His version was originally called “OCCAM3” to distinguish it from these earlier OCCAM incarnations; the “3” has finally been dropped.
OCCAM’s typical use is to analyze data involving a large number of discrete variables, but continuous variables can be accommodated if they are first discretized (binned). Models are developed which consist of one or more relations, which are then evaluated for their information content and statistical significance. OCCAM searches the lattice of possible models (exploratory analysis) or can do detailed analysis on a specific model (confirmatory analysis). In Variable-Based Modeling (VBM), model relations involve subsets of variables. In State-Based Modeling (SBM), relations also involve one or more specific states of variables.
OCCAM provides a web-based interface, which allows uploading a data file, performing analysis, and viewing/downloading results. It runs on a PSU server at http://dmit.sysc.pdx.edu/. The user uploads a data file to this server, provides input information on a web input page. When the computation is complete, OCCAM either returns .html output directly to the user or a .csv output file that can be read by a spreadsheet program such as Excel. If the computation is not likely to finish rapidly, the user can provide an email address and OCCAM will email the .csv output to the user when it is done. See OCCAM location & general use for more information.
OCCAM is now an open-source project with code at GitHub. At GitHub, the guide for installation is at https://github.com/occam-ra/occam ; the manual is at https://occam.readthedocs.io/en/latest/occam-user-manual.html
Since OCCAM is still transitioning to the open-source world, installation may not be as smooth as would be ideal. If you have any issues with the software or would like to contribute to the project, please contact us through the GitHub site.
Rights
OCCAM Manual, OCCAM version 3.4.1, © Copyright 2006-2025.
OCCAM is open source and available on GitHub: https://github.com/occam-ra/occam.
Persistent Identifier
https://archives.pdx.edu/ds/psu/33727
Citation Details
Software:
Martin Zwick, project director, Heather Alexander, Joe Fusion, and Kenneth Willett, programmers (2021) “OCCAM, a Reconstructability Analysis program.” Systems Science Program (now Complex Systems Program), Portland State University.
Manual:
Martin Zwick (2021), “OCCAM, A Reconstructability Analysis Program.” Systems Science Program (now Complex Systems Program), Portland State University.
Description
The download is a zipped folder of the OCCAM GitHub software. Below, as an Additional File, is the OCCAM Manual, last revised on 19 January 2021.