Within a single project tracking these metrics allows

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Unformatted text preview: in a substantial improvement in that probability. The risk management method requires an estimate of the probability distribution for the final TPM value. (See sidebar on tracking spacecraft mass.) Early in the TPM tracking program, when the demonstrated value is based on indirect means of estimation, this distribution typically has a larger statistical variance than later, when it is based on measured data, such as a test result. When a TPM stays along its planned profile (or equivalently, when its margin remains above the corresponding margin requirement), the narrowing of the statistical distribution should allow the TPM to remain in the green alert zone (in Figure 22(c)) despite its growth. The three methods represent different ways to assess TPMs and communicate that information to management, but whichever is chosen, the pattern of success or failure should be the same for all three. Relationship of TPM Tracking Program to the SEMP . The SEMP is the usual document for describing the project's TPM tracking program. This description should include a master list of those TPMs to be tracked, and the measurement and assessment methods to be employed. If analytical methods and models are used to measure certain high-level TPMs, then these need to be identified. The reporting frequency and timing of assessments should be specified as well. In determining these, the system engineer must balance the project's needs for accurate, timely, and effective TPM tracking against the cost of the TPM NASA Systems Engineering Handbook Management Issues in Systems Engineering tracking program. The TPM tracking program plan, which elaborates on the SEMP, should specify each TPM's allocation, time-phased planned profile or margin requirement, and alert zones, as appropriate to the selected assessment method. 4.9.3 Systems Engineering Process Metrics Status reporting and assessment of systems engineering process metrics provides additional visibility into the performance of the "system that produces the system." As such, these metrics supplement the cost and schedule control measures d...
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This document was uploaded on 02/26/2014 for the course E 515 at University of Louisiana at Lafayette.

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