Int. J. System of Systems Engineering, Vol. 5, No. 3, 2014 193 Copyright © 2014 Inderscience Enterprises Ltd. A histogram analysis for system of systems Raed M. Jaradat* and Charles B. Keating Department of Engineering Management and Systems Engineering, Old Dominion University, 2101 Systems Research and Academic Building, Norfolk, VA 23529, USA Email: rjama001@odu.edu Email: ckeating@odu.edu *Corresponding author Joseph M. Bradley 1133 Belmeade Dr, Virginia Beach, VA 23455, USA Email: josephbradley@leading-change.org Abstract: The problems stemming from increasing complexity continue to confound our capabilities to deal with systems. In response, many large organisations seek to integrate their existing systems to work together to accomplish capabilities that cannot be achieved by the constituent systems. The integration of these systems is often referred to as a system of systems (SoS). While much has been written about SoS and their associated phenomena, we have not found sufficient exploration to answer some of our most basic questions: where did this concept came from? And when, or has, the peak of the SoS development movement been reached? To answer these questions, this paper has constructed a histogram analysis to trace the history of SoS from 1926–2011. Five hundred different sources have been included in the analysis in an attempt to give a glimpse into the development of the SoS field through the frequency of publications. Keywords: complex systems; system of systems; SoS; histogram analysis; intervals; multidisciplinary problems. Reference to this paper should be made as follows: Jaradat, R.M., Keating, C.B. and Bradley, J.M. (2014) ‘A histogram analysis for system of systems’, Int. J. System of Systems Engineering, Vol. 5, No. 3, pp.193–227. Biographical notes: Raed M. Jaradat is a PhD candidate in the Department of Engineering Management and Systems Engineering at Old Dominion University (ODU) with research aligned at the National Centers for System of Systems Engineering (NCSoSE). His research interests include systems thinking and complex systems exploration, organisational behaviour problems, supply chain management and critical infrastructures, system dynamics, and risk management. He is a topic leader in systems thinking, including systems theory and complex systems, for the Society for Engineering and Management Systems (SEMS). Prior to joining the doctoral programme at ODU, he worked