What is Precedence Diagramming Method in Project Management?

What is Precedence Diagramming Method in Project Management?

With many complex responsibilities involved in handling a project, Project Management as a task has become even more challenging. With tools to assist that helps accomplish the project and executing the duties and supporting software, the widely used network techniques are more than half a century old. Thus, project managers should consider techniques or methods that best suit their management style.

This article provides an overview of the Precedence Diagramming Method including how to draw & create the Precedence Diagramming Method in Project Management.

What is the Precedence Diagramming Method (PDM)?

A strategy for scheduling activities in a project plan, the Precedence Diagramming Method (PDM) is a strategy for developing a project schedule network diagram that utilizes nodes to represent activities and associates them with projectiles that illustrate the dependencies. This method is likewise called the activity-on-node (AON).

Network diagram using Precedence Diagramming Method

Source: https://bit.ly/2ndp5K5

Alluding to a particular project management technique, the project team utilizes a schedule network diagramming procedure to graphically represent any acknowledged and preexisting schedule activities through the utilization of nodes.

The most significant advantage of using the Precedence Diagramming Method is that it quickly allows the project team to understand all the scheduled activities and its affiliates with each other.

How to Create the Precedence Diagramming Method (PDM)?

To build the Precedence Diagramming Method (PDM) the preliminary step in planning is to work on the Work Breakdown Structure. The entire project becomes more comfortable when you break down the tasks to perform the activities. Knowing the capacities that it is fundamental to finish the assignment on time, you likewise need to know in what order the project should be completed. To do this, we need to create a Precedence Diagram.

Below mentioned are a few steps that articulate on creating a Precedence Diagram:

  • Ensure that you have a whiteboard or flip-chart papers to draw your plan

  • Put the top deliverable from your work breakdown structure on to the right-hand side of the board or paper

  • Take each of the lowest level and post-it from your breakdown structure and arrange them in the order in which they need to happen.

  • Work from the left until you have the dependencies between the tasks and you have a sequence of functions running from left to right.

As a project manager, ensure that your emphasis is on project sequence. As you put effort on the activities, you may come across additional tasks that have to be performed, and henceforth you can incorporate the equivalent in the precedence diagram and to the work breakdown structure. At last draw bolts between the assignments that connect up, and ensure that there aren't any tasks sitting isolated.

How to create a precedence diagram

Source: https://bit.ly/2GeRSdp

Types of Precedence Diagramming Method Relationships

The significant output in the Sequence Activities process is the Network Diagram. Amidst the sequence activities process, the activities that are explained in the define activities process is sequenced as specific activities that rely upon another. While the network diagram shows the project activities and presents the interrelationships of activities, the Precedence Diagramming Method (PDM) is the most widely-recognized strategy to draw network diagrams. So it is normal for certain affiliates and dependencies between the activities in Precedence Diagramming Method.

With the precedence diagramming method, four types of relationships are used in the activities to complete the network diagram of a project. They are:

Precedence diagramming method

  • Finish-to-Start (FS) is the most common dependency type used between activities. Activity can't begin before a predecessor activity completes. At that point, a Finish-to-Start dependency needs to be present between these exercises.

  • Start-to-Start (SS) is a kind of dependency shows that two activities determine to start together.

  • Finish-to-Finish (FF) in a project illustrates that two activities in a project determine to finish together.

  • Start-to-Finish (SF), a unique type of dependency on projects, it can be utilized instantly along with the supply chain materials for instance. In this type of dependency, Activity B can finish only after Activity A starts.

Types of Dependencies in Precedence Diagramming Method

  • Mandatory Dependency is known as hard logic is an integral part of the work. For instance, if you’re working on a project, you cannot test a screen that is yet to be developed entirely in the project. Consequently, in this case, there is a mandatory dependency between the development and testing of the screen.

  • Discretionary Dependency also referred to as preferential or soft logic is controlled by the project team and can be changed to abbreviate the project. In this technique, activities stay the same, yet, the order changes.

  • External Dependency comes from outside of the project — for instance, a government regulation expected to finish before proceeding with the outstanding of the project activities.

  • Internal dependency is a method that involves a precedence relationship between project activities. For instance, if there are activities appointed to a member of the project team, he can't begin to work on that until the previous project finishes even though there is not a mandatory dependency.

Example of Precedence Diagramming Method

A visual representation technique which is used to prepare the project schedule network diagrams here is a Precedence Diagramming Method Example that analyzes the basic.

Precedence Diagramming Method Example

In the example mentioned above, activities are indicated as A, B, C, D, F, G, H, I. Durations are the numbers mentioned above the boxes. Activity B is a predecessor activity that logically comes before a dependent activity F in this network system. Activity F is a successor activity a dependent activity that inevitably occurs after the Activity F. There is an F-S Relationship between activity B and F.

Step 1: PDM Forward Pass Calculation specify the minimum dates at which each activity can be performed and, ultimately, the minimum duration of a project.

PDM Forward Pass Calculation

Step 2: PDM Backward Pass Calculation determine the latest dates by which each activity can be performed without increasing the projects minimum duration.

PDM Backward Pass Calculation

Step 3: PDM Float Calculation for Each Activity

PDM Float Calculation for Each Activity

Total float is the amount of time that an activity can be delayed without delaying the project completion date. Total float is 0 on the critical path.

Total Float: LS – ES = 17-7 = 10
Total Float: LF – EF = 27-17 = 10

The total float can be calculated by subtracting the Early Start date of activity from its Late Start date or Early Finish date from its Late Finish date.

Step 4: PDM Identifying the Critical Path

PDM Identifying the Critical Path

When we analyze the network diagram, we will see that there are some paths and every path have duration.

(Example and image source: https://bit.ly/2RUpgYo)

The Precedence Diagramming Method, with its activity-on-node network and additional precedence relationships, offers a simpler and increasingly adaptable system way to deal with demonstrating large projects. While PDM enhances the project planner's ability to deliver precisely demonstrate large projects, clients ought to know about and ready to adequately manage its highlights.


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