Critical Path Analysis Starter The Big Breakfast On

Critical Path Analysis

Starter – The Big Breakfast! • On Saturday, I want to cook myself a big breakfast. I want to have some toast, scrambled eggs and some bacon. • It takes me 3 minutes to make the toast It takes 1 minute to break and whisk the eggs and then I need to put them in the microwave for a further 3 minutes. The grill takes 2 minutes to heat and bacon takes 4 minutes to cook under the grill. The breakfast takes me 1 minute to serve and a further 10 minutes to eat. Once I have eaten my breakfast I need to wash up which takes a further 2 minutes and then put the plates away which takes 2 minutes. • What is the quickest time I can do this in?

1 Put the grill on 2 Put the bread in the toaster 3 Whisking the eggs takes 1 minute 4 Put the eggs in the microwave – need to be in for 3 minutes 4 Once the grill is ready I put the bacon in – total time so far is two minutes 5 The toast is ready after 3 minutes and the eggs are ready after a total of 4 minutes 6 The bacon finishes after 6 minutes – 6 minutes so far 7 The breakfast takes 1 minute to serve – 7 minutes so far 10 – It takes 10 minutes to eat – 17 minutes so far 11 – Washing up and putting away takes 4 minutes – 21 minutes Why is it simply not a case of adding up all the times to get a total?

Simple example

Planning and Monitoring Tool

Critical Path Analysis (CPA) Key term: A technique for planning complex projects to allow them to be completed in the shortest time possible by identifying activities that can be carried out simultaneously.

Advantages of CPA • Helps reduce the risk and costs of complex tasks • Should improve efficiency • Encourages careful assessment of the requirements of each activity in a project • Help spot which activities have some slack (float) • A decision making tool – helps with other aspects of business planning (e. g. cashflow forecasting and budgeting)

Disadvantages of CPA • Reliability of CPA depends on accurate estimations • Limited usefulness on large, complex projects • CPA does not guarantee the success of a project • Too many activities may make the network diagram too complicated. Activities themselves may need to be broken down into mini-projects

The Process

CPA – the Process • Identify and prioritise the activities • Identify which activities MUST be done before others • EST – identify earliest start time • LFT – identify latest finish time • Identify the FLOAT – tasks which can be completed outside the critical path • Identify the critical path – points connecting ESTs and LFTs (where these are the same)

Critical Path Analysis Node numbers showing order of activities in the left hand semi-circle of each node. 1 A 3 The Critical Path 2 Earliest Start Time (EST) 3 B 5 5 Arrows indicate the order of the tasks, the letter above shows the order, the time period below the arrow Latest Finish Time (LFT) Nodes: Show the start and finish of a task

Nodes and activities Activity 1 EST LFT The node shows the physical start and finish of an activity paint wall 2 Time 3 hrs EST LFT The arrow shows us the actual task which is being undertaken

Constructing the network 2 The first job 1 2 1 Start the project 4 Start the next activities 3 Finish the job

Building a network 3 1 2 5 Complete tasks 3 &4 4 6 Start the next activity once both 3 & 4 are complete

The completed diagram 7 Finish the job 3 1 2 5 4 6 Give each node a number

Adding the information Add the activities and times b a 1 2 24 hrs 3 3 hrs 7 hrs d 3 hrs c f 5 e 4 6 3 hrs 2 hrs

The earliest start times Add the earliest start times a 1 0 b 2 24 24 hrs 3 27 3 hrs 7 hrs d 3 hrs c 5 34 e 4 27 f 3 hrs 2 hrs 6 37

The latest finishing times 0 1 0 a 24 hrs 3 27 27 b 2 24 24 3 hrs c 7 hrs d 5 e 4 27 32 2 hrs 34 34 f 3 hrs 6 37 37 Add the latest finishing times

The critical path * a 1 0 0 24 hrs *b 2 24 24 3 27 27 * 3 hrs 7 hrs d e 3 hrs 4 27 32 * c 5 34 34 2 hrs f 3 hrs 37 6 37 Critical activities are a, b, c, f.

The float • With the network complete, you can now identify any idle time. • This spare time is known as the float. • Resources can be allocated to other duties during the float time. • In this activity there is only one critical time between tasks d and e, where there are 5 floating hours. • Float is calculated by: Float = LFT – (EST - Duration)

Good news!! You will not be required to complete a CPA diagram from scratch, you will be asked to complete some elements (ESTs and LFTs) of a partially-finished diagram

Plenary – CPA Revision Quiz • http: //www. tutor 2 u. net/blog/index. php/busi ness-studies/comments/revision-quiz-criticalpath-analysis