Critical Path Analysis

Last Updated: September 3, 2010

That’s ‘Project Management’ to You and Me!

Introduction

Businesses are constantly working on projects and from your own experience, you will know that management is very important. There are a number of methods that can be used to successfully manage a project, but we will be focusing on one particular aspect – time: extremely important to all businesses we acknowledge.

An unexpected delay or similar time crisis can put a business under a lot of pressure and perhaps it was all unforeseeable: evidence of poor project management?

So, how can you plan your time and identify where delays could occur, leaving you to make decisions to compensate for such situations? A useful tool to use would be the CRITICAL PATH ANALYSIS.

Critical Path Analysis – What is it ?

The critical path analysis is a tool that illustrates the individual tasks of a project highlighting the expected starting and finishing tasks of each. More precisely, the critical path analysis can be used to:

Estimate the minimum/maximum time that tasks will be started and completed
Estimate the minimum time that the whole project will take to complete
Identify if resources are not being used effectively
Make aware any tasks that could create a possible delay

Ultimately, the critical path analysis will suggest which tasks are critical to keep on time anticipating that the delay in any one of the tasks will delay the whole project. The critical path analysis is hard to explain in more detail without the use of diagrams, and so the working example in the following section will make it all more clear.

Example

XYZ Limited have decided to carry out some research to ultimately create a selling strategy for their new product. They have decided to create a questionnaire, which they will issue to the public personally. In addition, they will use a mail shot to send out a similar survey to get the opinions of those that live outside of the area. Each task (A – F) has been given an expected completion time (in weeks). Time is crucial for XYZ Limited and so the Manager has requested a Critical Path Analysis of the project

Task	Description	Order/Logic	Time
A	Plan Primary Research	To be completed first	1 wks
B	Prepare Mail Shot (Postal Survey)	Start when A is complete	3 wks
C	Prepare Questionnaire	Start when A is complete	2 wks
D	Send and Wait for Mail Shot Replies	Start when B is complete	3 wks
E	Issue Questionnaire	Start when C is complete	3 wks
F	Compile and Analyze Results	Start when D & E is complete	2 wks
G	Plan Selling Campaign	Start when D, E & F is complete	2 wks

Now, take a good look at the diagram below. Each circle (Node) will be used to enter specific data. The numbers currently in the nodes (1 – 7) are only there to make following the diagram easier – nothing more. The arrows represent the tasks and each is given their respective completion times.

Before we move on, look at the above table again and ensure that you understand what is being said by linking it back to the diagram. Basically, all tasks cannot start until the previous task has been completed. This is not true for tasks B and C which can start at the same time – this is the only tricky area. First of all, we have to identify the earliest starting time (est) for each task. This figure is then entered into the top right hand segment of the node. To work out the est’s, we move from left to right on the diagram. The diagram below shows all the est’s for the project and by hovering the mouse over a node, it will show how this figure was obtained.