Critical path analysis Flashcards
Define critical path analysis.
CPA is a management tool which helps a business to identify how long a project will take and what the critical tasks in that project are
The diagrams are called network diagrams, as they show a network of tasks in a project
What are the uses of critical path analysis?
CPA can be used to schedule a building project, for example the roof is not the first thing to go on a house and the site may not have enough room for all the roof tiles at the start.
A building business would therefore schedule the tiles to be delivered when they are needed perhaps on week three when the roof goes on
CPA can also be used:
- Launch a new product onto a market.
- A photo shoot of the new product would not happen on day 1 so a schedule would be useful so bookings can be made
- Installation of new technology in a business
- Renovation of old buildings
- Advertising campaigns
What are the benefits of critical path analysis?
Stakeholders will be able to see the total time frame for the project to be completed
Parallel activities can be scheduled, for example electricians can work on the lighting in the kitchen while the plasterers put plaster on the upstairs walls. This will save time on the project
Very useful for businesses in the FMCG (Fast Moving Consumer Goods) markets where speed is important
Useful to know when to deliver resources or arrange for labour to arrive e.g. can’t put a carpet in while painters are still working
How do critical path analysis diagrams work?
A CPA network diagram starts with a list of tasks
It will show how long each task will take (duration)
It will also show what order they should be carried out (preceding activities) e.g. You can’t ice a cake until it’s baked
The start of the diagram is the first day, shown bu a circular node. The number shows the node number, not the day.
The top right hand corner shows the earliest starting time and the bottom right hand corner shows the latest finishing time.
Lines between nodes show each task to be carried out.
How do you calculate EST?
The previous EST + the duration of the last task. Where 2 nodes meet, choose the longest EST.
How do you calculate LFT?
Go backwards, subtracting duration from the last node’s LFT. Where 2 nodes meet, take the shortest.
How do you identify the critical path?
The critical path is the one which takes the longest and is indicated with 2 lines.
The EST = LFT in the critical path.
How do you calculate float time?
When nodes are the same top and bottom there is no spare time so these tasks are critical
If these tasks are delayed they will delay the whole project
So we need to know where there is some free time or “float”
Float time= LFT-EST
What are the limitations of critical path analysis?
All the data in the network diagram is based on estimates and can quickly become inaccurate e.g. if the weather turns bad on a building project or suppliers fail to turn up with a delivery
The drawing up on a diagram is time consuming it may be quicker to get on with the project
The project may be simple and not require a diagram
