Last Updated 10/22/2001
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In software estimation, it is important to recognize the strong relationships between Costs,Schedule and Quality. They form three sides of the same triangle. Beyond a certain point (the "Quality is Free" point), it is difficult to increase quality without increasing either the costor schedule or both for the software under development. Similarly, development schedule cannot be drastically compressed without degrading the quality of the software product and/or increasingthe cost of development. Software estimation models can play an important role in facilitatingthe balancing of these three factors.
COQUALMO (COnstructive QUALity MOdel)--formerly called CODEFMO--isan estimation model that can be used for predicting number of residual defects/KSLOC (Thousands ofSource Lines of Code) or defects/FP (Function Point) in a software product. It can be applied in the earlyactivities such as analysis and design, as well as in the later stages for refining the estimate when more information is available. It enables 'what-if' analyses that demonstrate the impact of various defectremoval techniques and the effects of personnel, project, product and platform characteristics on softwarequality. It also provides insights into determining ship time, assessment of payoffs for quality investments andunderstanding of interactions amongst quality strategies.
The model depicted in Figure 1 shows that defects conceptually flow into a holding tank through various defect-sourcepipes and are drained off through various defect-elimination pipes. The defect source pipes are modeled as the "Software Defect Introduction Model" and the defect elimination pipes are being modeledas the "Software Defect Removal Model". For more details read usccse98-515.ps.
The model is expert-judgement based and the data collection activity has been started. We hope to get enough datapointsto validate and calibrate the model by the year 2000.
The key factor is continuing to improve the predictive accuracy of COQUALMO is good data. To that end, we areasking for the help of the software industry in collecting data. If you or the organization you work for has the ability to supplysoftware development project data, we would like to hear from you. The benefit to you for participating in data collection will be theavailability of a more accurate predictive model for estimating your software project costs. Additionally, you will have the opportunityto participate in the COQUALMO oriented workshops being planned at USC, and to receive calibrated versions of the implemented model before the general public.
For your convenience, we are providing below for download copies of the COCOMO® II data collection instrument, and the standard data nondisclosure agreementUSC-CSE enters into with most of our data suppliers.
For further information or to discuss participation in the COQUALMO data collection program, please contact us.
Data Collection Documents:
Primary funding and technical support of the development of COQUALMO has been provided by theUSC-CSE Affiliates. We would like to take this opportunity to acknowledge their generous assistance, without whose help the development of COQUALMO would have been impossible.
For an extensive bibliography of software cost estimation related papers and books gohere.
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