PERT and Gantt charts are visualization tools that are often used in project management. Both of these charts are used for task scheduling, controlling, and administering the tasks necessary for the completion of a project. The difference between them is that a PERT chart is a kind of network diagram, while a Gantt chart is a bar chart. Show What is the PERT Chart?PERT Chart is an acronym for (Program Evaluation and Review Technique). A PERT chart is a project management tool used to schedule, organize, and coordinate tasks within a project. It is a method to analyze the tasks involved in completing a given project, especially the time needed to complete each task and to identify the minimum time needed to complete the total project. What is a Gantt Chart?A Gantt chart is a type of horizontal bar chart commonly used in project management, which is a visual view of tasks scheduled overtime. It provides a graphical visualization of a schedule that helps to plan, coordinate, and track specific tasks (or elements) in a project. Gantt chart boils down multiple tasks and timelines into a single page. Using a Gantt chart allows all stakeholders to perceive the same schedule information, sets mutually understood expectations, and conducts their efforts according to the desired protocol. The Gantt chart tool provides a visual timeline for the start and end of tasks, making it clear how tasks are interrelated and perhaps rely on the completion of another before one can start. PERT vs Gantt ChartPERT charts are network diagrams that use boxes to represent tasks and arrows to present dependencies between tasks. The boxes are laid out from left to right, but there is no fixed Y-axis with dates. The first box, or root, is centered vertically on the left side, and the subsequent tasks can be drawn anywhere along the Y-axis. Arrows can point to the right, up or down, but never to the left. Gantt charts are bar graphs. The X-axis contains dates and the Y-axis lists separate tasks. On each line of the Y-axis, the chart depicts a bar positioned to extend from the task’s start date to its end date. Tasks are listed in the start-date order. PERT vs Gantt ExampleA Pert Chart: The ‘Gantt Chart version” of the PERT Chart above: SummaryBecause the PERT Chart clearly illustrates task dependencies, a PERT chart sometimes is preferred over the Gantt chart (another popular project management charting). While the PERT chart can be harder to interpret, especially for large-scale projects. Most often, project managers use both techniques in order to serve multiple purposes. On the contrary, a Gantt chart does not show clear dependencies or relationships between tasks and also fails to provide enough information for showing the critical path and as well as the detail information for each of the activities. We can summarize the differences between the two as listed in the table below:
A PERT chart, sometimes called a PERT diagram, is a project management tool used to schedule, organize and coordinate tasks within a project. It provides a graphical representation of a project's timeline that enables project managers to break down each individual task in the project for analysis. The PERT chart template uses nodes -- drawn as rectangles or circles -- to represent events and milestones throughout the project. The nodes are connected by vectors -- drawn as lines -- which represent the various tasks that need to be completed. PERT charts provide project managers with an estimation of the minimum amount of time needed to complete a project. Managers can also analyze the work breakdown and task connections, as well as assess the risk associated with the project. The breakdown structure makes it easy to organize a complex project with a variety of moving parts by visualizing the dependencies between each step of the process. PERT stands for Program Evaluation Review Technique, a methodology developed by the U.S. Navy in the 1950s to manage the Polaris submarine missile program. A similar methodology, the critical path method (CPM) was developed for project management in the private sector at about the same time. TerminologyHere is a list of terms associated with PERT charts:
How a PERT chart worksA PERT chart presents a graphic illustration of a project as a network diagram consisting of numbered nodes linked by labeled vectors. The direction of the arrows on the lines indicates the sequence of tasks. When creating a PERT chart, project managers should follow the below steps:
Once the PERT chart is drawn, project managers can use it to develop a realistic time frame for the project:
A breakdown of a PERT chart In the diagram, for example, the tasks between nodes 1, 2, 4, 8 and 10 must be completed in sequence. These are called dependent or serial tasks. The tasks between nodes 1 and 2 and nodes 1 and 3 are not dependent on the completion of one to start the other and can be undertaken simultaneously. These tasks are called parallel or concurrent tasks. Tasks that must be completed in sequence but that don't require resources or completion time are considered to have event dependency. These are represented by dotted lines with arrows and are called dummy activities. For example, the dashed arrow linking nodes 6 and 9 indicates that the system files must be converted before the user test can take place but that the resources and time required to prepare for the user test -- writing the user manual and user training -- are on another path. Numbers on the opposite sides of the vectors indicate the time allotted for the task. When to use a PERT chartPERT charts should be used when a project manager needs to:
Project managers find best results when they use a PERT chart at the beginning of the project. Doing so helps ensure the project is accurately scoped and can help avoid any potential bottlenecks in the process. Advantages of PERT chartsProject managers use PERT charts to gain these benefits:
Disadvantages of PERT chartsDisadvantages of the PERT chart include the following:
PERT chart vs. Gantt chartThe PERT chart is sometimes preferred over the Gantt chart, another popular visual tool for project managers, because it clearly illustrates task dependencies. On the other hand, the PERT chart can be more difficult to interpret, especially on complex projects. Frequently, project managers use both techniques.
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