PROJECT MANAGEMENTApproaches

By- Rahul Jain

Network analysis

Network analysis is the general name given to certain specific techniques which can be used for the planning, management and control of projects.

One definition of a project:

“A project is a temporary Endeavour undertaken to create a "unique" product or service”

PERT

PERT estimate the shortest possible time each activity will take, the most likely length of time, and the longest time that might be taken if the activity takes longer than expected.

PERT - Project Evaluation & Review Techniques

USED IN : Project management - for non-repetitive jobs (research and development work), where the time and cost estimates tend to be quite uncertain. This technique uses probabilistic time estimates.

Why Pert

• What tasks must be carried out. • Where parallel activity can be performed. • The shortest time in which you can complete a project. • Resources needed to execute a project. • The sequence of activities, scheduling and timings

involved. • Task priorities. • The most efficient way of shortening time on urgent

projects.

PERT- Estimated time

Step 1 : Estimate : To, Tp, Tm

Step 2: Find Estimated time Te:(Shortest time (To) + 4 x likely time (Tm) +

longest time (Tp) )/6

Step 3: Estimate Variance Variance = {[tp-to]/6}2 sd= square root of variance Step 4: Z= (Due date-Expected date)/Std dev.

(Te-Tm)/Sd

If z is positive then more than 50% chance of completing the project on time.

Time

To= Optimistic time can be less than 10% to 20% of normal time .

Tp= Pessimistic time can be more than 10% to 20% of normal time .

CPM - Critical Path Method

• Definition: In CPM activities are shown as a network of precedence relationships using activity-on-node network construction– Single estimate of activity time– Deterministic activity times

USED IN : Production management - for the jobs of repetitive in nature where the activity time estimates can be predicted with considerable certainty due to the existence of past experience.

Critical Path Method

• Is that the sequence of activities and events where there is no “slack” i.e.. Zero slack

• Longest path through a network• minimum project completion time

CPM

• ADVANTAGES:– Precedence relationships– large projects– more efficient

Some keyterms

• There are several key terms– Critical Path: The longest time path through the task network. The series of

tasks (or even a single task) that dictates the calculated finish date of the project (That is, when the last task in the critical path is completed, the project is completed) The "longest" path (in terms of time) to the completion of a project. If shortened, it would shorten the time it takes to complete the project. Activities off the critical path would not affect completion time even if they were done more quickly.

– Slack Time: The amount of time a task can be delayed before the project finish date is delayed. Total slack can be positive or negative. If total slack is a positive it indicates the amount of time that the task can be delayed without delaying the project finish date. If negative, it indicates the amount of time that must be saved so that the project finish date is not delayed. Total Slack = Latest Start - Earliest Start. By default and by definition, a task with 0 slack is considered a critical task. If a critical task is delayed, the project finish date is also delayed. (Also known as float time )

12

CPM

• Critical Path Analyses are presented using circle and arrow diagrams.

• In these, circles show events within the project, such as the start and finish of tasks. The number shown in the left hand half of the circle allows you to identify each one easily. Circles are sometimes known as nodes.

• An arrow running between two event circles shows the activity needed to complete that task. A description of the task is written underneath the arrow. The length of the task is shown above it. By convention, all arrows run left to right. Arrows are also sometimes called arcs.

The Project Network

• Use of nodes and arrows

Arrows An arrow leads from tail to head directionally– Indicate ACTIVITY, a time consuming effort that is required to perform a part

of the work.

Nodes A node is represented by a circle- Indicate EVENT, a point in time where one or more activities start and/or

finish.

Activity on Node & Activity on Arrow

Activity on Node

- A completion of an activity is represented by a node

Activity on Arrow

- An arrow represents a task, while a node is the completion of a task

- Arrows represent order of events

Benefits of CPM/PERT

• Useful at many stages of project management• Mathematically simple• Give critical path and slack time• Provide project documentation• Useful in monitoring costs

Questions Answered by CPM & PERT

• Completion date?• On Schedule?• Within Budget?• Critical Activities?• How can the project be finished early at the least cost?

exampleIllustration of network analysis of a minor redesign of a product and its associated packaging.

The key question is: How long will it take to complete this project ?

For clarity, this list is kept to a minimum by specifying only immediate relationships, that is relationships involving

activities that "occur near to each other in time".

•"What activities must be finished before this activity can start"

•could we complete this project in 30 weeks?

•could we complete this project in 2 weeks?

One answer could be, if we first do activity 1, then activity 2, then activity 3, ...., then activity 10, then activity 11 and the project would then take the sum of the activity completion times, 30 weeks.

“What is the minimum possible time in which we can complete this project ? “

Before starting any of the above activity, the questions asked would be

We shall see below how the network analysis diagram/picture we construct helps us to answer this question.

CRITICAL PATH TAKES 24 WEEKS FOR THE COMPLETION OF THE PROJECT

Limitations to CPM/PERT

• Clearly defined, independent and stable activities• Specified precedence relationships• Over emphasis on critical paths

Thank you