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2 - PROJECT LIFE CYCLE AND ORGANIZATION

evolution, replacement, and retirement of a software product. Enhancement and adaption of the initially delivered
software may involve several project life cycles beyond the initial one. This Software Extension to the PMBOK
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Guide covers software project life cycles.

According to Section 2.4 of the PMBOK Guide, “A project life cycle is the series of phases that a project
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passes through from its initiation to its closure. The phases are generally sequential.” Section 2.4 of this Software
Extension describes the ways in which software project life cycles are similar to and different from the project life
cycles presented in the PMBOK Guide.
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Section 2.4 of the PMBOK Guide also states that project life cycles occupy a continuum from predictive to
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adaptive. Factors that characterize the positions of life cycles for software projects within the continuum include
(but are not limited to) the various ways requirements and plans are handled, how risk and cost are managed, and
the involvement of key stakeholders. The continuum of life cycles for software projects is illustrated in Figure 2-1.
Highly predictive software project life cycles are characterized by emphasis on specification of requirements and
detailed planning during the initiation and planning phases of a software project. Detailed plans based on known
requirements and constraints reduce risk and cost. Milestones for key stakeholder involvement are also planned.

Highly adaptive life cycles for software projects are characterized by progressive specification of requirements
based on short iterative development cycles. Risk and cost are reduced by progressive evolution of initial plans; key
stakeholders are continuously involved.

The following considerations apply to the middle area of the predictive-adaptive continuum: (a) risk and cost
are reduced by iterative evolution of initial plans; and (b) key stakeholders have more opportunities to be involved
in predictive-adaptive iteration cycles than stakeholders at the typically infrequent project milestones of highly
predictive life cycles. However, stakeholders in predictive-adaptive projects have fewer opportunities to be involved
than key stakeholders who are continuously involved in highly adaptive life cycles.

Highly Predictive Adaptive Highly
Predictive Adaptive
• Requirements are • Requirements are • Requirements are
specified during elaborated at periodic elaborated at frequent
initiation and planning intervals during intervals during
• Risk and cost are software development software development
controlled by detailed • Risk and cost are • Risk and cost are
planning based on controlled by controlled as
in-depth analysis of progressively detailed requirements and
requirements and planning based on constraints emerge
constraints prior to timely specification of • Key stakeholders are
development requirements and continuously involved
• Key stakeholders are constraints during
involved at scheduled development
milestones • Key stakeholders are
involved at specified
intervals

Figure 2-1. The Continuum of Software Project Life Cycles

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