Schedule Development

Numerous projects was unsuccessful
to meet schedule prediction
because of lack of schedule development   to overcome
this. There are methods which used for project schedule. Such as critical path method and PERT method

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1. Critical path method (CPM)

This
is the method which is used calculate the time duration which is taken by
project. The critical path method help to estimate the time which used to
schedule development. Critical method used by many organization to estimate the
time duration because in a single project there are multiple tasks running simultaneously
CPM able to show which task take how much time to complete . there are two way
to calculate CPM forward pass and backward pass .Which help to estimate earliest
time for the project the longest path is consider as Critical path . Because it
included all Critical element.

The
Critical path method is network diagram which have nodes in it .Every node have
task and value assigning to it by find the relationship between the node and after
calculating the node value we come to know the Critical path

 

For example:

The critical path is the chain of activities with
the longest time taken duration. A slow up in
any of these activities will result in a delay for the whole project. This critical path example help us to
understand the how this method work.

                                                                                                                      

 

 

 

Using the Critical Path Method (CPM)

The
duration of each activity is listed above each node in the diagram. For each
path, add the duration of each node to determine it’s total duration. The
critical path is the one with the longest duration.

 

 

 

There
are three paths through this project.

Start
-> Activity1->Activity3->Activity4->finish                              3+7+2=12

Start
-> Activity2->Activity3->Activity4->finish                              5+7+2=14    (Critical Path)

Start
-> Activity2->Activity5-> finish                                                5+4=9

 

Advantages of CPM

·        
Makes dependencies visible between the project
activities

·        
Increases visibility of impact of schedule revisions

·        
Enables the Project Manager to optimize efficiency

Disadvantages of CPM

·        
For large and complex projects, there’ll be thousands of
activities and dependency relationship

·        
The Critical Path Method does not account
for resource and resource allocation

        

2. Program Evaluation and Review Technique (PERT)

Second method is PERT .It was initially used
by defiance in their Polaris project .In this method the activities time
duration is found.

By using these following formula:

Duration       = 

And,

Standard Deviation    =       

This network analysis is a method used to approximate
project time duration when there is a unpredictability
occurs in the individual activity time duration approximates. PERT applies the
critical path method (CPM) to a weighted average time duration approximate.
This approach was developed about the same time as CPM, in the late 1950s, and
also uses network diagrams concept, which are still sometimes referred to as
PERT charts. PERT uses probabilistic time approximates duration. Approximation
based on using optimistic time, most likely time and pessimistic time approximates
of activity durations instead of one specific or discrete duration approximate,
as CPM does .By using the PERT weighted average for each activity duration approximate,
the total project duration approximate takes into account the risk or
uncertainty in the individual activity estimate.

 

For example:

Suppose a project team in the project case
used PERT to determine the schedule for the online application registration
system project. They would have to collect data for the optimistic, most
likely, and pessimistic duration approximates for each project activity. Suppose
one of the activities was to design an input screen for the system. Someone
might approximate that it would take about two weeks or 10 workdays to do this
activity. Without using PERT, the duration approximate for that activity would
be 10 workdays. Using PERT, the project team would also need to approximate the
pessimistic and optimistic times for completing this activity. Suppose an
optimistic approximate is that the input screen can be designed in eight workdays,
and a pessimistic time approximate is 24 workdays.

Applying the PERT formula:

PERT weighted average = 

                                                       

                                         = 12

Instead of using the most likely duration approximate
of 10 workdays, the project team would use 12 workdays .These additional two
days could really help the project team in getting the work completed on time.

Advantage of PERT

·        
A PERT chart makes planning
large projects easier

·        
PERT is a way of making
relationships visible in a diagram

·        
PERT makes the critical path
visible

Disadvantage of PERT

·        
PERT charts can be
complicated and confusing, with hundreds or even thousands of tasks and
dependency relationships

·        
PERT diagrams can be expensive
to develop, update and maintain.

·        
PERT charts depend on the
ability to predict precise time frames for multitudes of tasks