In software projects upward confirmation of solutions

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Unformatted text preview: put under configuration management at the various control gates. Off-core activities, analyses, and models are used to substantiate the core decisions and to ensure that the risks have been mitigated or determined to be acceptable. The off-core work is not formally controlled, but the analyses, data and results should be archived to facilitate replication at the appropriate times and levels of detail to support introduction into the baseline. There can, and should, be sufficient iteration downward to establish feasibility and to identify and quantify risks. Upward iteration with the requirements statements (and with the intermediate products as well) is permitted, but should be kept to a minimum unless the user is still generating (or changing) requirements. In software projects, upward confirmation of solutions with the users is often necessary because user requirements cannot be adequately defined at the inception of the project. Even for software projects, however, iteration with user requirements should be stopped at the PDR, or cost and schedule are likely to get out of control. Modification of user requirements after PDR should be held for the next model or release of the product. If significant changes to user requirements are made after PDR, the project should be stopped and restarted with a new vee, reinitiating the entire process. The repeat of the process may be quicker because of the lessons learned the first time through, but all of the steps must be redone. Time and project maturity flow from left to right on the vee. Once a control gate is passed, backward iteration is not possible. Iteration with the user requirements, for example, is possible only vertically, as is illustrated on the vee. NASA Systems Engineering Handbook The Project Life Cycle for Major NASA Systems Integration and Verification. Ascending the right side of the vee is the process of integration and verification. At each level, there is a direct correspondence between activities on the left and right sides of the vee. This is deliberate. The method of verification must be determined as the requirements are developed and do...
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