Precedence Diagramming Method (PDM) || Project Estimation

In our previous videos we have learnt how to use decomposition techniques to create work breakdown structure.

The lowest level of WBS is used more accurately for understanding the dependencies and applying estimation techniques .

In this video , we will understand how to convert the list of activities into sequence of activities for logical understanding and estimation thereby increasing the efficiency of project planning.

Precedence Diagramming Method is a technique used to construct a schedule model in which activities are represented by nodes and are graphically linked by one or more logical relationships to show the sequence in which the activities need to be performed.

PDM includes four types of dependencies:

Before delving deep into the four types of dependencies , let us understand the terms Successor and Predecessor.

A predecessor activity is an activity that logically comes before a dependent activity.

A successor activity is a dependent activity that logically comes after another activity.

First and the most commonly used dependency is Finish to Start.
A successor activity cannot start until a predecessor activity has finished.
For example, before installing software, you need to install the hardware drivers, and before that, the hardware must be assembled.”

Next is Finish to Finish:
A successor activity cannot be finished until the predecessor activity is not finished.

For example, Software Testing cannot finish until the Development is completed.

Start to Start:

In this type of dependency relation, Successor activity cannot start until the Predecessor activity starts.

For example, Testing cannot start until the Development activity has not started.

If you observe, in the above case the same scenario falls under both types of dependencies. This may occur , however choose the best relation to avoid multiple relationships.

Start to Finish.

In this rare type of dependency , a predecessor activity cannot finish until the successor activity has started.

For example, a new module has to be started before de-commissioning an old module

By using this technique, project managers can build logical sequences for efficient project planning."

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