This paper examines five foundational concepts in project management: the triple constraint (time, cost, scope), the systems approach to organizational analysis, the systems development lifecycle (SDLC) and its predictive and adaptive models, task dependencies and their four types, and the theory of constraints. Each concept is explained with practical examples and interconnections, providing a framework for understanding how projects are structured, planned, and executed across multiple disciplines and environments.
The term triple constraint refers to three interdependent factors that act as constraints on the way projects are completed. The triple constraints, which may also be called the project triangle, are found in all projects. These factors are time, cost, and scope. Successful projects are usually defined as those delivered at the right time, within the correct budget, and to the specified scope. These different influences converge, and to understand their interrelationship, each factor may be considered individually, followed by a discussion of how they influence each other.
The time constraint refers to the timescale in which the project should be delivered, meeting the required completion schedule. For a project to be delivered on time, effective time management must be exercised throughout the project, ensuring that each stage is completed on schedule to facilitate timely progression. Project managers will utilize project planning models, which may include software, to facilitate planning. These models aid in the development of work breakdown structures, which identify the different tasks that need to be undertaken and the prerequisites that can be used to create an effective plan. The project manager must assess project progress to ensure that different stages are completed on time, and if the project falls behind, there must be a reassessment of the schedule in order to bring the project back on track.
Cost refers to the monetary investment and relates to the project budget. A successful project is completed within budget, rather than exceeding that budget. Good planning for projects will usually include a contingency fund in case there are any unexpected expenses. While the emphasis in terms of financial cost usually refers to achieving the project within budget, it should also be noted that where there is a significant underspend, this should be investigated to ensure compliance with the relevant quality requirements.
The dimension of scope refers to the end goal of the project and what it is meant to provide. Successful projects start out with a clear and concise project definition, including what it should be, what it should provide, and a process that is important in order to minimize the potential for changing boundaries as the project progresses. Therefore, it may also be necessary to define what the project will not incorporate.
There is an inherent interdependency between these factors. For example, the broader the scope of the project, the greater the potential cost and time required to complete it. Likewise, if there is a need to cut the budget, this may reduce the scope of the project. If a project is required quickly or if it falls behind schedule, and the project must be delivered on time, it may be necessary to use more resources—for example, bringing in additional labor—which in turn will increase costs. Alternatively, if a lagging project is still required on time but there is no additional budget, the scope of the project may be reduced. Where one of these constraints is impacted directly or indirectly, it will invariably influence the other constraints.
The concept of the systems approach views the organization as a system. Systems are made up of internal dependent parts or processes, and they may be either closed or open. A closed system is completely self-contained and does not interact with its environment and is not impacted by that environment. An open system, by contrast, will interact with the external environment through the presence of inputs, throughputs, and outputs. A good example of an open system is an animal: it is a living creature which interacts with its environment through inputs, such as food and oxygen, which are then processed internally to provide energy, and creates outputs, such as carbon dioxide from breathing and bodily waste, which are returned to the environment. A car is an example of a mechanical system, reliant on the acquisition of fuel and the skills of a driver to operate, and it provides an output service as well as emissions.
The analogy of an open system can be applied to an organization. The organization will be made up of a number of internal dependent parts and processes which operate together and will also be reliant on inputs, throughputs (which may also be considered transformational processes), and outputs. The application of open systems theory to organizations usually assumes that the boundaries of the organization are more flexible and ambiguous compared to some other types of systems, and that some components within the system—for example, the people—may be part of multiple systems.
Applying a systems approach to the commercial environment allows observers to see organizations as part of a more complex environment. This perspective considers the way in which different input influences—such as raw materials, labor, legislation, the competitive environment, and geographical factors—may influence the organization's choices and performance. It also examines how throughputs are managed and how outputs manifest. The process is not simply one of observation, but can also be used in a more proactive manner to determine how certain changes may have impacts and how the organization may manage or react to influences in order to maintain and improve their position.
Systems development lifecycle (SDLC) is a framework which outlines the stages for the management of the development process for systems. In all development processes, the same core stages must be undertaken: initiation, planning, analysis, design, implementation, and deployment. A number of different models exist which may classify these stages in different ways, but this represents the generally accepted approach. Initiation is the beginning of the project and includes the activities which start the process, including the identification of the need for the project, approval for the project, and allocation of finance. Planning can only take place after the project has been initiated, and this includes the definition of the project—identifying the scope, planning what will take place and when through scheduling, and identifying the resources that will be required. Analysis involves activities such as understanding the requirements of the users. The design stage provides a definition for the solution the project will provide, including its structure. Implementation involves programming activities and other processes required to create the solution and its database. Deployment includes the actions required for data conversion, final testing, and the placement of the system into production or use.
The process may be undertaken with one of two approaches: the predictive approach or the adaptive approach. The predictive approach is used where the project has well-understood requirements and is assessed as a low technical risk, with the plan for the system set out in advance. The waterfall method of systems development is a predictive model, where each stage is frozen as it is completed, and there is no backtracking or revisiting of processes to adapt them after they are completed. In the waterfall approach, there is no overlap between the different phases of the project. In a modified waterfall approach, there is recognition that the different phases or stages may overlap.
The adaptive approach provides a much greater level of flexibility and may be used when there are uncertainties regarding the requirements and needs for the project and where there may be a higher level of technical risk. Unlike the predictive model—which assumes that the process may be planned in advance—the adaptive approach assumes that not all planning can occur in advance. Instead, the process adapts and changes as the project progresses. This also allows for a greater level of overlap between the phases of the project. The agile and spiral models are both adaptive SDLCs.
In a project, there is a need to identify dependencies between different tasks. Some tasks require other elements of the project to be completed before they can progress. For example, one cannot test a system before it has been coded, just as one cannot start to build a house before the land has been purchased. There may be many different dependencies within a project. Identifying them aids with planning and the development of the work breakdown schedule and the development of a Gantt chart, which will show the critical path.
There are four different types of dependencies: finish to start, start to start, finish to finish, and start to finish. These indicate the type of relationship that exists between two tasks. Finish to start means that a preceding task must be finished before the next task can start. For example, before a house can be built, the land must be purchased and the purchase finalized. The start to start dependency is where a predecessor must have been started before the next task can start. For example, in building a road, the excavation needs to start before the road can be tarred. The finish to finish dependency requires that the preceding task must be finished before the subsequent task can be finished. Using the example of the road, the tarmac in the road must be completely finished before the painting of the white lines can be completed. The final dependency is start to finish, where a preceding task must be started before the subsequent task can be finished. In the case of the road construction example, the excavation of the road must have started before the painting of the white lines can be finished.
In project management, there are likely to be a number of interdependent relationships where dependencies may be based on several preceding or succeeding tasks. The most common type is finish to start, where one stage must be finished before another stage can start. The least common dependency is the start to finish dependency. Dependencies may also be categorized as hands-off dependencies, which is a finish to start dependency, or resource dependencies where there is a reliance on resources that are being used for previous tasks; they cannot take place until the resources needed are available.
"Identifying and optimizing system bottlenecks"
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