Tom Gilb

An American systems engineer, consultant, and author, Tom Gilb was known for the development of software inspection, evolutionary processes, and software metrics—a quantitative measure of the degree to which a software system or process possesses some property. Since quantitative measurements are essential in all sciences, there was a continuous effort by computer science practitioners and theoreticians to bring similar approaches to software development. The goal was obtaining objective, reproducible, and quantifiable measurements, which had numerous valuable applications in schedule and budget planning, cost estimation, quality assurance testing, software debugging, software performance optimization, and optimal personnel task assignments.

Gilb was also the inventor of Planguage, a formal, natural language modelling notation which adds rigour to the requirement documentation. He was directly recognized as the idea source for parts of the Agile and Extreme programming methods, primarily the incremental cycles. Born in Pasadena, California, USA, he emigrated to the United Kingdom in 1956 and to Norway in 1958.

He took his first job with IBM in 1958, where he worked for five years, and became a freelance consultant in 1960. Gilb worked mainly within the software engineering community, but from 1983 also addressed Corporate Top Management problems, and from 1988 worked with large-scale systems engineering in the areas of Aircraft, Telecoms, and Electronics. His methods were widely and officially adopted by many organizations such as IBM, Nokia, Ericsson, HP, Intel, and Citigroup, among many other large and small organizations.

He was a member of the International Council on Systems Engineering (INCOSE; pronounced in-co-see), a non-profit membership organization dedicated to the advancement of systems engineering and to raising the professional stature of systems engineers. Gilb was active in the Norwegian chapter, NORSEC, and lectured at INCOSE local chapters on his worldwide travels and at INCOSE conferences. In 2012 he was made an Honorary Fellow of the British Computer Society.

He worked as a consultant, teacher, and author in partnership with his son Kai Gilb. Gilb primarily helped multinational clients improve their organizations and methods by using "Evolutionary Systems Delivery" (Evo). He guest lectured at universities across the UK, Europe, China, India, USA, and Korea, and also served as a keynote speaker at dozens of technical conferences internationally.

Gilb wrote nine books and several articles, a few of which include: "Software Inspection," 1993, ISBN 0-201-63181-4; "Principles of Software Engineering Management," 1988, ISBN 0-201-19246-2 (19th printing); "Software Metrics (Winthrop computer systems series)," 1977; and "Competitive Engineering: A Handbook for Systems & Software Engineering Management using Planguage," 2005, ISBN 0-7506-6507-6. He published hundreds of papers, and one paper—"Laws of Unreliability," Datamation, March 1975—presented his Laws of Unreliability, which garnered over 22,000 Google hits.