precedence diagram

The precedence diagramming method refers to a specific project management which is a graphical representation technique, that shows the inter-dependencies among various project activities. The main advantage of precedence diagramming method is that it shows the activity dependencies, and it can be an important communication tool for stakeholders.

The precedence diagramming method consists of rectangles, known as nodes, and the project activities are shown in these boxes. These rectangular boxes are connected to each other with arrows to show the dependencies; therefore, these diagrams are also known as the Activity on Node diagrams.

Precedence Diagramming Method

There are four dependencies which are used in Precedence Diagram Method:

  1. Finish to Start (FS)
  2. Finish to Finish (FF)
  3. Start to Start (SS)
  4. Start to Finish (SF)

Finish to Start (FS)

This type of dependency is the most commonly used dependency in the diagramming techniques. The second activity cannot be started until the first activity completes.

For example, to paint a wall you first need to build a wall. In this case, the first activity is building the

wall and second activity will be painting. You cannot start painting the wall unless the wall is ready.

Finish to Finish (FF)

Here, the second activity cannot be finished until the first activity finishes. In other words, both activities should finish simultaneously.

For example, let us say that you coding a program for a client, and the client is providing you the characteristics of the program. In this case, you cannot finish coding for your program until the client gives you his complete requirements. Here, both activities should finish simultaneously.

Start to Start (SS)

Here, the second activity cannot be started until the first activity starts. Both activities should start simultaneously.

Suppose you have to apply a primary coating on a wall. To apply the coating, you also need to clean the wall. Therefore, one team will start cleaning the wall and second team will paint it. Both activities can be started at the same time.

Start to Finish (SF)

In this dependency, the second activity cannot be finished until the first activity starts.

For example, let us say you have to move into a new home, and your old home has to be demolished. In this case, you cannot move to your new home until it is ready. Hence, the second activity (construction of new home) must be finished before the first activity starts (you start moving into a new home); for example, if you are living in old home and you are moving into your new home, you cannot start vacating your old home until the new house is completely ready.

Although this type of dependency is not commonly used, you as a project manager should know about all the types of dependencies. It is very critical for you, and as a project manager, to accept all types of dependencies because it will help you greatly when drawing the network diagram and then creating the project schedule.

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