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Project Management

Concepts

Mayank Singh

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Step Wise: An Approach to Planning

Software Projects

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Activity Planning● A detailed plan for the project must also

include a schedule indicating start and completion times for each activity.

● This will enable us:– Ensure that appropriate resources will be

available when required.– Avoid different activities competing for the same

resources at the same time.– Produce a timed cash flow forecast.– Produce a detailed schedule showing which staff

carry out each activity.

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Objectives of Activity Planning

● Feasibility assessment – Is the project possible within required timescales and resource constraints?

● Resource Allocation – What are the most effective way of allocating resources to the project and show availability?

● Detailed costing – How much will the project cost?

● Motivation● Coordination

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Project and activities● Defining activities● Identifying activities: Three approaches

to indentifying activities or task that make up a project.– Activity based approach– Product based approach– Hybrid approach

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Activity based approach● Creating a list of activities that may be

involve in project.● To show this we can create WBS.

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WBS● Dividing complex projects to simpler and

manageable tasks is the process identified as Work Breakdown Structure (WBS).

● Usually, the project managers use this method for simplifying the project execution.

● In WBS, much larger tasks are broken-down to manageable chunks of work.

● These chunks can be easily supervised and estimated.

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Product based approach● It produces product breakdown structure

and product flow diagram (PFD).

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Product based approach● It produces product breakdown structure

and product flow diagram (PFD).

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Hybrid approach● Till now, we have seen WBS which is

based on entirely on a structuring of activities.

● Another is based on the project’s products which is based on a simple list of final deliverables.

● Now we can combine both WBS which shows the structuring product and activities.

● This structure is based on deliverables.

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Sequencing and scheduling activities

● Throughout a project, we will require a schedule that clearly indicates when resources it will need.

● We will create a chart which shows the development process and the resources that are available.

● In chart, we have sequenced the tasks and scheduled them.

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Network planning models● These project scheduling techniques model

the project’s activities and their relationships as a network.

● These techniques were developed in 1950s.

● Two techniques are:– CPM (Critical Path Method)– PERT (Program Evaluating Review Technique)

● Recent variation of these techniques are known as Precedence Networks.

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Formulating a network model

● The first step is to represent the activities and their interrelationships as a graph.

● In CPM, this is done by representing activities as links (Arrowed Lines) in the graph.

● Nodes (Circles) representing the events of activities starting and finishing.

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Project activity network with a checkpoint activity

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Project activity network as CPM

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Constructing CPM networks

● A project network may have only one start node.– All activities coming from that node may start immediately resources are

available.– They do not have to wait for any other activities to be completed.

● A project network may have only one end node.– The end node designates the completion of the project.– A project may only finish once.

● The first step is to represent the activities and their interrelationships as a graph.

● In CPM, this is done by representing activities as links (Arrowed Lines) in the graph.

● Nodes (Circles) representing the events of activities starting and finishing.

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Constructing CPM networks

● A link has duration– Link represents an activity.– Activities takes time to execute.– Shows the order in which activities are to be

carried out.● Nodes have no duration.

– Nodes are events and are instantaneous points in time.

– Source node is the event for ready to start.– Sink node is the event for completion.

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Constructing CPM networks

● Node 3 is the event that both coding and data take-on have been completed and activity program testing is free to start.

● Installation may be started only when event 4 has been achieved as soon as program testing has been completed.

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Constructing CPM networks

● Time moves from left to right– Time moves from left to right.

● Nodes are numbered sequentially– No precise rules about node numbering.

● A network may not contain loops

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Constructing CPM networks

● A network may not contain dangles– A dangling activities like Write User Manual

cannot exist.● Precedents are the immediate preceding

activities

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Example 1● State what is wrong with each of them and

where possible redraw them correctly.

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Example 1● Activity D dangles, giving the project two ‘end

events’.

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Example 2● State what is wrong with each of them and

where possible redraw them correctly.

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Example 2● Once again, this network has two end nodes,

but in this case the solution is slightly different since we should introduce a dummy activity if we are to follow the standard CPM conventions.

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Example 3● State what is wrong with each of them and

where possible redraw them correctly.

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Example 3● Either this one has a dangle or activity E has its

arrow pointing in the wrong direction.● We need a bit more information before we can

redraw this one correctly.

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Example 4● State what is wrong with each of them and

where possible redraw them correctly.

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Example 4● There is noting wrong with this diagram.● It is just badly drawn and the nodes are not

numbered according to the standard conventions.

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Example 5● State what is wrong with each of them and

where possible redraw them correctly.

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Example 5● This one containing a loop.● F cannot start before G has finished.● G cannot start before E has finished and● E cannot start before G has finished.● One of the arrow is wrong.

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Using dummy activities● When two paths within a network have a common

events although they are independent, gives a logical error.

● Suppose that it is necessary to specify a certain piece of hardware before placing an order for it and before coding the software. Before coding the software it is also necessary to specify the appropriate data structures, although we do not need to wait for this to be done before the hardware is ordered.

● .

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Using dummy activities● Above model is incorrect in that it requires both

hardware specification and data structure design to be completed before either an order may be placed or software coding may commence.

● We can resolve this problem by separating the two independent paths and introducing a dummy activity to link.

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Using dummy activities● Dummy activities shown as dotted lines.● It have a zero duration and use no resources.

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Representing lagged activities

● If we wish to undertake two activities in parallel so long as there is a lag between the two.

● When activities can occur in parallel with a time lag between them we represent these with pairs of dummy activities..

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Adding the time dimension● Now we are ready to start thinking about when

each activity should be undertaken.● CPM is concerned with two primary objectives:

– Planning the project so that it is completed as quickly as possible.

– Identifying those activities where a delay is likely to affect the overall end date of the project.

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Adding the time dimension● We have an estimate of each activity duration.● Then network is analyzed by carrying out a

forward pass – to calculate the earliest dates at which activities may commence and the project be completed.

● Backward pass – to calculate the latest start dates for activities and the critical path.

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CPM Conventions● The diagram is used to record information

about the event rather than the activities.● Activities based information is generally held on

a separate activity table.● Most used convention is labeling nodes.● Nodes are divided into 4 quadrant.

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Example● An example project specification with estimated

activity durations and precedence requirements.

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Example● Draw an activity network using CPM

conventions for the project specified in above table.

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Forward pass● Forward pass is carried out to calculate the

earliest date on which each event may be achieved.

● And the earliest date on which each activity may be started and completed.

● The forward pass and the calculation of earliest start dates is calculated according to the following reasoning.

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Forward pass● Activity A, B, and F may start immediately, so

the earliest date for event 1 is ZERO and the earliest date for these three activities is also zero.

● Activity A will take 6 weeks, so the earliest it can finish is week 6. so the earliest can achieve event 2 is week 6.

● Activity B will take 4 weeks, so the earliest it can finish and the earliest we can achieve event 3 is week 4.

● Activity F will take 10 weeks, so the earliest it can finish is week 10.

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Forward pass rule● The earliest date for an event is the earliest

finish date for all the activities terminating at that event.

● When more than one activity terminated at a common event we take the latest of the earliest finish dates for those activities.

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CPM Network Forward pass

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Activity table after Forward pass

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Backward pass rule● Second stage is to carry out a backward pass to

calculate the latest date at which each event may be achieved, and each activity started and finished, without delaying the end date of the project.

● Latest date for an event is the latest date by which all immediately following activities must be started for the project to be completed on time.

● We assume that the latest finish date for the project is the same as the earliest finish date.

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Backward pass rule● The latest date for an event is the latest start

date for all the activities that may commence from that event.

● Where more than one activity commences at a common event we take the earliest of the latest start dates for those activities.

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Backward pass

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Backward pass