Passing the #PMP Exam—Study Group Discussions (Chapter 2—Product Life Cycle vs. Project Life Cycle)

PMBOK® Guide Chapter 2 deals with taking a project and showing how it is interrelated with the larger environment in which a organization does business. The first topic to be discussed below is the relationship of the product life cycle, the project life cycle, and the project management process.

 1. Overview—definitions

How does the PMBOK® Guide define these terms?



Product life cycle Collection of generally sequential, non-overlapping product phases whose name and number and determined by the manufacturing and control needs of the organization.
Project life cycle Collection of generally sequential project phases whose name and number are determined by the control needs of the organization.
Project management process Collection of five iterative project management process groups that includes inputs, tools & techniques, and outputs.

The first two definitions are taken from the PMBOK® Guide, and the last one is a definition I created extrapolating from other definitions for similar terms.

There are quite a few similarities between the product life cycle and project life cycle definition, so the trick in not confusing them is to a) understand their purpose, and b) focus on the differences.

2. Product life cycle

Product life cycle management says that a product goes through various phases: market introduction, growth, maturity, saturation and decline. These happen one after another, and there is no overlap between them. Since a project creates a unique product, service, or result, you can have a situation where a project exists but there is no product, i.e., in the case where it produces a service or result.

Similarly, there are parts of a product life cycle which may not require a project. Certainly the creation or design of a new product, or perhaps even a new model of an existing product, would require a project. Once the product is being mass produced, however, and the manufacturing becomes a routine part of the operational work of a company, then a project may no longer be necessary.

A product life cycle is sequential and non-overlapping, meaning that they occur like this in a linear fashion:

Fig. 1. Product life cycle

2. Project life cycle

One of the problems in any project, especially a large one, is that the cost of making a change in the project scope increases as time goes on, and not in a linear way. So making a change late in the project has HUGE consequences. To gain control over a large project, it is often divided into phases. These are sequential, but as opposed to a product life cycle, can SOMETIMES overlap. Here’s an example where the phases are sequential and non-overlapping:

Fig. 2. Non-overlapping project phases

Time Period




Project Phase




And here’s a more complicated case where they are overlapping:

Fig. 3. Overlapping project phases

Time Period




Project Phase

← Phase 1 →

←           Phase 2             →
← Phase 3 →

3. Product life cycle ↔ Project life cycle relationship

A product in its single phase of development to market can be split up into several projects, such as the hypothetical example below, EACH of which would go through its own complete process.

Fig. 4. Single phase of a product cycle (market introduction) broken up into several discrete projects.

Note that each of these projects could be combined into one large project with each of these projects now becoming phases, each having a start, beginning, and end.

4. Project management process

One of the differences between the project life cycle and the project management process is a distinction which the Rita Mulcahy book encapsulates as the following, which was very helpful for our group in distinguishing the two.

Project life cycle How you do the work

(i.e., how you split up to do it easier)

Project management process How you manage the work

(what processes do you perform to get it done)

The five processes of the project management process are:

  1. Initiating process group
  2. Planning process group
  3. Executing process group
  4. Monitoring & controlling process group
  5. Closing process group

Although the project always starts with the initiating process group, then goes to the planning group, and ends with the closing process group, the executing, monitoring and closing process and the planning process again can be repeated in a cycle called an iteration as illustrated below:

Fig. 5. Planning, Executing, and Monitoring & Controlling Process Group

If the monitoring shows that the project is off of its schedule or budget, an act of controlling it and steering it back to the project baseline will occur. If it can be done without changing any of the original plans or baseline of the project, then it would go from ACT back to DO. But if the project plans now have to be changed because the change is a substantial one, then the PLAN must be done again in order to reset the baseline. Of course when the final deliverable has been produced, then and only then do you go on to the final process, the closing process.

So it is more proper to say the process groups are iterative than sequential.

In sum, it is important to distinguish between

  • A product life cycle and a project life cycle (always sequential and non-overlapping vs. SOMETIMES sequential and non-overlapping)
  • A product and a project (project can be a product OR a result or service)
  • A project life cycle and a project management process (phase vs. process)

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