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QUANTIFYING THE IMPACT OF REQUIREMENTS VOLATILITY ON SYSTEMS
ENGINEERING EFFORT
by
Mauricio Eduardo Peña
A Dissertation Presented to the
FACULTY OF THE USC GRADUATE SCHOOL
UNIVERSITY OF SOUTHERN CALIFORNIA
In Partial Fulfillment of the
Requirements for the Degree
DOCTOR OF PHILOSOPHY
(INDUSTRIAL AND SYSTEMS ENGINEERING)
August 2012
Copyright 2012 Mauricio Eduardo Peña
Object Description
| Title | Quantifying the impact of requirements volatility on systems engineering effort |
| Author | Peña, Mauricio Eduardo |
| Author email | mauriziopena@yahoo.com;mauricip@usc.edu |
| Degree | Doctor of Philosophy |
| Document type | Dissertation |
| Degree program | Industrial and Systems Engineering |
| School | Viterbi School of Engineering |
| Date defended/completed | 2012-04-30 |
| Date submitted | 2012-07-06 |
| Date approved | 2012-07-06 |
| Restricted until | 2012-07-06 |
| Date published | 2012-07-06 |
| Advisor (committee chair) |
Boehm, Barry Settles, Stan |
| Advisor (committee member) |
Valerdi, Ricardo Ghanem, Roger |
| Abstract | Although changes in requirements are expected as part of a system’s development, excessive volatility after the requirements baseline is likely to result in cost overruns and schedule extensions in large complex systems. Furthermore, late changes in requirements may cause significant rework of engineering products and lead to project failure. Changes in requirements should be expected, accounted for and managed within the context of the system of interest. Unfortunately, system developers lack adequate methods and tools to anticipate and manage the impact of volatile requirements, and cost estimating techniques often fail to account for their economic consequences. ❧ This dissertation presents an extension to COSYSMO, a generally-available parametric systems engineering cost model, which incorporates requirements volatility as a predictor of systems engineering effort within COSYSMO’s structure and scope with the aim of improving the model’s cost estimation capabilities. The requirements volatility model extension was developed through a combination of expert judgment gathered through surveys and discussions in six different research workshops and historical data collected from 25 projects. The null hypothesis that the volatility of requirements throughout a system’s life cycle is not a statistically significant predictor of systems engineering effort was rejected in factor of the alternative hypothesis with a P-value of 0.03. A comparison of the estimation accuracy of COSYSMO to that of the model that includes volatility effects shows an improvement in predictive accuracy from 52% to 80% at the PRED (20) level and a reduction in the mean magnitude error (MMRE) from 21% to 16%. In addition, the coefficient of determination between the predictor, systems engineering size adjusted for diseconomies of scale, and the response, actual systems engineering effort improved from an R2 of 0.85 to an R2 of 0.92 when the volatility factor was applied to the model. ❧ In addition to the mathematical model that quantifies the impact of volatility on systems engineering effort; the contributions of the research include a-) a set of project organizational, technical, and contextual factors ranked by subject matter experts in terms of their influence on requirements volatility; b-) the operationalization of the requirements volatility parameter in COSYMO through a 5-point rating scale; c-) a documented set of observations, developed from the literature and the research workshops, that describe the behaviors and effects of requirements volatility throughout the system life cycle. |
| Keyword | systems engineering; requirements volatility; COSYSMO |
| Language | English |
| Part of collection | University of Southern California dissertations and theses |
| Publisher (of the original version) | University of Southern California |
| Place of publication (of the original version) | Los Angeles, California |
| Publisher (of the digital version) | University of Southern California. Libraries |
| Provenance | Electronically uploaded by the author |
| Type | texts |
| Legacy record ID | usctheses-m |
| Contributing entity | University of Southern California |
| Rights | Peña, Mauricio Eduardo |
| Access conditions | The author retains rights to his/her dissertation, thesis or other graduate work according to U.S. copyright law. Electronic access is being provided by the USC Libraries in agreement with the author, as the original true and official version of the work, but does not grant the reader permission to use the work if the desired use is covered by copyright. It is the author, as rights holder, who must provide use permission if such use is covered by copyright. The original signature page accompanying the original submission of the work to the USC Libraries is retained by the USC Libraries and a copy of it may be obtained by authorized requesters contacting the repository e-mail address given. |
| Repository name | University of Southern California Digital Library |
| Repository address | USC Digital Library, University of Southern California, University Park Campus MC 7002, 106 University Village, Los Angeles, California 90089-7002, USA |
| Repository email | cisadmin@usc.edu |
| Archival file | uscthesesreloadpub_Volume4/etd-PeaMaurici-917.pdf |
Description
| Title | Page 1 |
| Contributing entity | University of Southern California |
| Full text | QUANTIFYING THE IMPACT OF REQUIREMENTS VOLATILITY ON SYSTEMS ENGINEERING EFFORT by Mauricio Eduardo Peña A Dissertation Presented to the FACULTY OF THE USC GRADUATE SCHOOL UNIVERSITY OF SOUTHERN CALIFORNIA In Partial Fulfillment of the Requirements for the Degree DOCTOR OF PHILOSOPHY (INDUSTRIAL AND SYSTEMS ENGINEERING) August 2012 Copyright 2012 Mauricio Eduardo Peña |
