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11b_Zen in the Art of COSYSMO (Valerdi)



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Zen in the Art of Cost Estimation Ricardo Valerdi Massachusetts Institute of Technology rvalerdi mit edu Copyright 2008 by Ricardo Valerdi Published and used by APCOSE with permission Abstract Engineering cannot wait until all phenomena are explained Engineers may work effectively often for centuries with heuristics This paper provides over thirty heuristics that have been inspired by the development and application of a systems engineering cost estimation model The objective of this paper is to present such heuristics in a simple manner so that they can benefit those that develop calibrate and use cost models Introduction This paper provides a collection of heuristics or small nuggets of wisdom to help systems engineers along the road of cost estimation in the same way Zen Buddhism encourages seeing deeply into the nature of things by direct experience The Zen monks taught that in every menial task there is something to be learned and something that the student can later meditate on The Zen monks believe that one can gather knowledge from all things in life While Zen began in China in the 6th century and spread to Japan Vietnam Korea and eventually the Western world several authors have made the connection between Zen and other activities such as motorcycle maintenance Pirsig 1974 flying Shade 1975 golf Hebron 1990 writing Bradbury 1992 fatherhood Lewis 1997 comedy Sankey 1998 flower arrangement Herrigel 1999 and even tennis Koran 2002 Arguably the most popular example is the text Zen in the Art of Archery Herrigel 1948 which was written by German philosopher Eugen Herrigel 1884 1955 Since its first German edition in 1948 the book has been translated into several foreign languages English Japanese Portuguese etc and has been continually reprinted as one of the best selling works on Japanese culture As a result the term Japanese archery evokes thoughts of spiritual training and Zen spirituality Yamada 2001 Heuristics A heuristic is a method to help solve a problem commonly informal It is particularly used for a method that often rapidly leads to a solution that is usually reasonably close to the best possible answer Heuristics are rules of thumb educated guesses intuitive judgments or simply common sense In more precise terms heuristics stand for strategies using readily accessible though loosely applicable information to control problem solving in human beings and machines Heuristics are common in psychology philosophy law and engineering A commonly used heuristic is If you are having difficulty understanding a problem try drawing a picture In psychology heuristics are simple efficient rules hard coded by evolutionary processes Heuristics have been proposed to explain how people make decisions come to judgments and solve problems typically when facing complex problems or incomplete information These rules work well under most circumstances but in certain cases lead to systematic cognitive biases Because heuristics are fallible it is important to understand their limitations They are only intended to be used as aids in order to make quick estimates and preliminary process designs Their applicability is also limited by the context under which they were derived Heuristics in Systems Architecting Engineering In engineering a heuristic is an experience based method that can be used as an aid to solve specific problems Endres Rombach 2003 By using heuristics time can be reduced when solving problems which may be very valuable While heuristics are not always scientifically validated they represent many years of empirical observations of experienced professionals packaged in the form of concise wisdom One area of engineering that has benefitted from heuristics is the field of systems architecting as a result of Eb Rechtin s 1926 2006 book Systems Architecting Creating and Building Complex Systems Rechtin 1991 The book contains a spectrum of more than 100 heuristics that provide insights in the areas of systems architecting development testing and organizations which were derived from Rechtin s 40 year career at NASA Jet Propulsion Laboratory Defense Advanced Research Projects Agency the Department of Defense the Aerospace Corporation and Hewlett Packard An example heuristic provided by Rechtin is Don t assume that the original statement of the problem is necessarily the best or even the right one This heuristic suggests the need for deeper analysis of solutions It works well when problem and solution are not too far apart that is when a few leaps of imagination may bring problem and solution together Heuristics Based Cost Model COSYSMO the Constructive Systems Engineering Cost Model is a parametric model that was developed for the purpose of estimating the cost of systems engineering effort in large complex systems The model enables the estimation of systems engineering effort through an assessment of system characteristics such as Number of System Requirements Number of System Interfaces Number of System Specific Algorithms Number of Operational Scenarios Additionally the systems engineering aspect of projects can be assessed for the following cost performance characteristics Requirements Understanding Architecture Understanding Level of Service Requirements Migration Complexity Technology Risk Documentation and diversity of installations platforms of recursive levels in the design Stakeholder team cohesion Personnel team capability Personnel experience continuity Process capability Multi site coordination Tool Support These characteristics are representative of the most influential systems engineering cost drivers as defined by industry experts and validated by through historical data Valerdi 2005 COSYSMO was inspired by a number of Rechtin s heuristics which eventually led to a software implementation of the model hereafter referred to as the tool that was used by several aerospace and defense organizations in the United States The tool is an important milestone because it enables the use of the model in a way that can be modified by different organizations to fit their needs In the process of helping organizations tailor the model a number of observations and lessons learned were captured which were eventually formalized into heuristics These heuristics were tested across different organizations for their validity and were reworded for clarity and scope User experience confirmed Rechtin s heuristics in many ways as will be discussed in the next section The general flow of these


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