palestine university - gaza faculty of business and finance project scheduling techniques, defining...

Palestine university - GazaFaculty of Business and Finance

Project Scheduling Techniques, Defining and Sequencing of

Project DeliverablesChapter 5

Instructor: Mosab I. Tabash

Project Management

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Recall The Triple Constraint of Project Management

Importance of Project Schedules

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Time Constraints: Restrictions set on the start or finish date of a task. You can specify that a task must start on or finish no later than a particular date.

Constraints can be flexible (not tied to a specific date) or inflexible (tied to a specific date)

Flexible constraints such as As Soon As Possible (ASAP) and As Late As Possible (ALAP) do not have specific dates associated with them.


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Setting these constraints allows you to start tasks as early as possible or as late as possible with the task ending before the project finish, given other constraints and task dependencies in the schedule.Inflexible constraints such as Must Start On (MSO) and Must Finish On (MFO) require an associated date, which controls the start or finish date of the task. These constraints are useful when you need to make your schedule take into account external factors, such as the availability of equipment or resources, deadlines, contract milestones, and start and finish dates.


• Managers often cite delivering projects on time as one of their biggest challenges

• Time has the least amount of flexibility; it passes no matter what

• Schedule issues are the main reason for conflicts on projects, especially during the second half of projects (Empirical Data).


Conflict Intensity Over the Life of a Project

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ProjectFormation

Early Phases Middle Phases End Phases

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Priorities

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Technical opinions

Procedures

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Personality conflicts

AverageTotal Conflict

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• Frustration with cost & schedule overruns• Management challenges exist today:

– Only 44% of projects are completed on time– On average, projects are 189% over-budget– 70% of completed projects do not perform as expected– 30% of projects are canceled before completion– On average, projects are 222% longer than expected

• The Standish Group, and represent the US national average for 1998


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includes the processes required to ensure timely completion of the project.

Project Time Management

1. Activity Definition—identifying the specific activities that must be performed to produce the various project deliverables.

2. Activity Sequencing—identifying and documenting interactivity dependencies.

3. Activity Duration Estimating—estimating the number of work periods that will be needed to complete individual activities.

4. Schedule Development—analyzing activity sequences, activity durations, and resource requirements to create the project schedule.

5. Schedule Control—controlling changes to the project schedule.

Project Management Knowledge Areas

Project Schedules-Activity Definition

• Where do Project Schedules come from?• Project schedules grow out of the basic

document that initiate a project– Project charter includes start and end dates and

budget information– Scope statement and WBS help define what will be

done

• Activity definition involves developing a more detailed WBS and supporting explanations to understand all the work to be done

• Once tasks (from the WBS) and size/effort (from estimation) are known: then PM must build his/her schedule:

Primary objectives• Best time• Least cost• Least risk

Secondary objectives• Evaluation of schedule alternatives• Effective use of resources• Communications

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Project Schedules

Scheduling Assumptions• PM makes several key assumptions

– All tasks have distinct begin and end points– All estimates can be mathematically derived– Tasks must be able to be arranged in a defined sequence that

produces a pre-defined result– Resources may be shifted to meet need– Cost and time share a direct relationship (Cost of each activity is

evenly spread over time)– Time, of itself, has no value

• Duration: The time it takes for an activity to be completed, given the planned amount of material, labor and equipment.

• Precedence: – A task that must occur before another is said to have

precedence of the other

• Concurrence:– Concurrent tasks are those that can occur at the same

time (in parallel)

• Leads & Lag Time– Delays between activities– Time required before or after a given task

Scheduling Definitions

• Milestones– Have a duration of zero– Identify critical points in your schedule– Shown as inverted triangle or a diamond– Often used at “review” or “delivery” times– Or at end or beginning of phases

• Ex: Design Requirements Review (SRR)• Ex: Contract Sign-off• Can be tied to contract terms

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Scheduling Definitions

Milestones

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Milestone Chart

• Sometimes called a “bar chart”

• Simple Gantt chart– Either showing just highest summary bars

– Or milestones only

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Sample Gantt Chart

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Sample Airline Gantt Chart

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Sample Bar chart

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Gantt Chart

Copyright Course Technology 2001

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MS Project Gantt Charts• Gantt charts provide a standard format for displaying

project schedule information by listing project activities and their corresponding start and finish dates in a calendar format

• Symbols include:– A black diamond: milestones or significant events on a

project with zero duration

– Thick black bars: summary tasks

– Lighter horizontal bars: tasks

– Arrows: dependencies between tasks

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Gantt Chart for Software Launch Project


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Sample Tracking Gantt Chart

white diamond: slipped milestone two bars: planned and actual times

Gantt Chart

• Disadvantages– Does not show interdependencies well

– No uncertainty of a given activity (as does PERT)

• Advantages– Easily understood

– Easily created and maintained

• Note: Software such as MS Project now shows dependencies among tasks in Gantt charts

• In the “old” days, Gantt charts did not show these dependencies; bar charts typically do not

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Task Dependency Relationships

• Finish-to-Start (FS)– B cannot start till A finishes

– A: Construct fence; B: Paint Fence

• Start-to-Start (SS)– B cannot start till A starts

– A: Pour foundation; B: Level concrete

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Task Dependency Relationships

• Finish-to-Finish (FF)– B cannot finish till A finishes

– A: Add wiring; B: Inspect electrical

• Start-to-Finish (SF)– B cannot finish till A starts (rare)

Task Dependency Types- Ms Project

Project Network Diagrams• Developed in the 1950’s

• A graphical representation of the tasks necessary to complete a project

• Visualizes the flow of tasks & relationships

• Project network diagrams are the preferred technique for showing activity sequencing

• A project network diagram is a schematic display of the logical relationships among, or sequencing of, project activities

Example• Planting trees with flowers and edging around them – tasks

required to complete this project:1. Mark utilities2. Dig Holes3. Buy trees4. Buy flowers5. Plant trees6. Plant flowers7. Buy edging8. Install edging

• This list does not reflect time or money• This list does not reflect task relationships• This list is a simple sequence of logical events• This list does not provide an easy project “snapshot”• Hard to see conflicts

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Planting trees with flowers and edging around themPlanting trees with flowers and edging around them

Example

Plant Trees

Mark Utilities

Buy Flowers

Buy Trees

Digging Holes

Buy Edging

Install Edging

Plant FlowersStart

Finish

Project Scheduling

• Mathematical Analysis– Network Diagrams

• PERT

• CPM

• GERT

• Bar Charts– Milestone Chart– Gantt Chart

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Mathematical Analysis

• PERT– Program Evaluation and Review Technique

• CPM– Critical Path Method

• Sometimes treated synonymously (Interchangeably)

• All are models using network diagrams

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MS-Project Example

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Network Diagrams• Two classic formats

– AOA: Activity on Arrow– AON: Activity on Node

• Each task labeled with– Identifier (usually a letter/code)– Duration (in standard unit like days)

• There are other variations of labeling

• There is one start & one end event

• Time goes from left to right

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Node Formats

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Duration

Activity

Node

Activity-on-Arrow (AOA) Network Diagram

• AOA consists of• Circles representing Events

– Such as ‘start’ or ‘end’ of a given task

• Lines representing Tasks– Thing being done ‘Build’

• a.k.a. Arrow Diagramming Method (ADM)• Nodes or circles are the starting and ending points of

activities• Can only show finish-to-start dependencies

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Activity-on-Arrow (AOA) Network DiagramThere are different Network Diagramming TechniquesSample Activity-on-Arrow (AOA) Network Diagram for Project X

Start End

Sample Activity-on-Node (AON) a.k.a Precedence Diagramming Method (PDM) Network Diagram for Project

Activity-on-Node (AON) Network Diagram

Process for Creating AOA DiagramsYou will have the list of the activities (WBS) , the precedence and duration.

1. Find all of the activities that start at node 1. Draw their finish nodes and draw arrows between node 1 and those finish nodes. Put the activity letter or name and duration estimate on the associated arrow

2. Continuing drawing the network diagram, working from left to right. Look for bursts and merges. Bursts occur when a single node is followed by two or more activities. A merge occurs when two or more nodes precede a single node

3. Continue drawing the project network diagram until all activities are included on the diagram that have dependencies

4. As a rule of thumb, all arrowheads should face toward the right, and no arrows should cross on an AOA network diagram

AOA Example

Activity Precedence Duration (weeks)

A - 1B - 2C - 3D A 4E B 5F B 4G C 6H D,E 6I G 2J H,I,F 3

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You decided to start your own business. You ended with the below list of activities and gave the Symbols from A-J. You want to have a network diagram for the project.


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Start End

AOA Example

Activity-on-Node (AON) Network Diagram

• Activity-on-Node (AON)

• Tasks on Nodes– Nodes can be circles or rectangles– Task information written on node

• •Arrows are dependencies between tasks

• •also.known.as. Precedence Diagramming Method (PDM)

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Precedence Diagramming Method (PDM)

• Activities are represented by boxes

• Arrows show relationships between activities

• More popular than ADM method and used by project management software

• Better at showing different types of dependencies

Critical Path

• “The specific set of sequential tasks upon which the project completion date depends”– or “the longest full path”

• All projects have a Critical Path

• Accelerating non-critical tasks do not directly shorten the schedule

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• 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.

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Critical Path

Critical Path Method (CPM)

• CPM is a project network analysis technique used to predict total project duration

• A critical path for a project is the series of activities that determines the earliest time by which the project can be completed

• The critical path is the longest path through the network diagram and has the least amount of slack or float


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Finding the Critical Path

• First develop a good project network diagram

• Add the durations for all activities on each path through the project network diagram

• The longest path is the critical path

Simple Example of Determining the Critical Path

• Consider the following project network diagram. Assume all times are in days.

2 3

4

5

A=2 B=5C=2

D=7

1 6

F=2

E=1

start finish

a. How many paths are on this network diagram?

b. How long is each path?

c. Which is the critical path?

d. What is the shortest amount of time needed to complete this project?

AOA Example

Activity Precedence Duration (weeks)

A - 1B - 2C - 3D A 4E B 5F B 4G C 6H D,E 6I G 2J H,I,F 3

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Back to our example, Find the critical path and determine the project durations

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Start End

AOA Example

Critical Path Method-Example

Start End

A-D-H-J1+4+6+3=11 DaysB-E-H-J2+5+6+3=16 DaysB-F-J2+4+3=9 DaysC-G-I-J3+6+2+3=14 Days

Critical Path

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Critical Path Method-Example

Activity Sequencing• Activity Sequencing• Involves reviewing activities and determining

dependencies:1. Mandatory dependencies: inherent in the nature of the

work; hard logic2. Discretionary dependencies: defined by the project team;

soft logic3. External dependencies: involve relationships between

project and non-project activities

• You must determine dependencies in order to determine the Project Duration and use critical path analysis


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More on the Critical Path

• If one of more activities on the critical path takes longer than planned, the whole project schedule will slip unless corrective action is taken

• Misconceptions:– The critical path is not the one with all the critical activities;

it only accounts for time

– There can be more than one critical path if the lengths of two or more paths are the same

– The critical path can change as the project progresses

Critical Path Example

• You found that Al-Adha Eid will come during your Spring Holiday. You found that this would be a great opportunity to benefit from this holiday and start a small business (Chocolates Shop) as most people will need to buy Chocolates During Eid. You finished your Feasibility Analysis and rent a small Shop in Al-Rimal. Use the Project Management Methodology to determine the time it will take you to start your business to know if you it will conflict with your exams.

Critical Path Example• Your First Step:

Design your (WBS):• 1.0 Financing:

– 1.1 Get Bank Loan

• 2.0 Prepare the Shop:– 2.1 Acquire Materials for Preparing the Shop– 2.2 Hire Painter– 2.3 Hire Carpenter– 2.4 Paint the Shop– 2.5 Finish the Decoration

• 3.0 Merchandising– 3.1 Purchase Chocolates from Retailers– 3.2 Deliver Chocolates to the Shop


Activity Precedence Duration

A-Get Bank Loan - 3

B-Acquire Materials A 2

C-Hire Painter B 2

D-Hire Carpenter B 3

E-Paint the Shop C 4

F-Finish the Decoration D 1

G-Purchase Chocolates from Retailers A 4

H-Deliver Chocolates to the Shop G 3

I-Shop Opening H,E,F 256

Your Second Step: Put Main Activities (Work Packages) in a tabular form for simplicity


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Your Third Step: Build your network Diagram and find the Critical Path

Duration in Days:Path 1: A-G-H-I Length=12Path 2:A-B-C-E-I Length=13Path 3:A-B-D-F-I Length=11Since the Critical Path is the longest path, Path 2 is the critical path. The Project Duration is 13 Days


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Program Evaluation and Review Technique (PERT)

• PERT is a network analysis technique used to estimate project duration when there is a high degree of uncertainty about the individual activity duration estimates

• PERT uses probabilistic time estimates based on using optimistic, most likely, and pessimistic estimates of activity durations


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Program Evaluation and Review Technique (PERT)

• PERT is a network analysis technique used to estimate project duration when there is a high degree of uncertainty about the individual activity duration estimates

• PERT uses probabilistic time estimates based on using optimistic, most likely, and pessimistic estimates of activity durations

Activity Duration Estimating

• After defining activities and determining their sequence, the next step in time management is duration estimating

• Duration includes the actual amount of time worked on an activity plus elapsed time

• People doing the work should help create estimates, and an expert should review them


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PERT Formula and Example

• PERT weighted average formula: optimistic time + 4X most likely time + pessimistic time

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• Example:PERT weighted average = 8 workdays + 4 X 10 workdays + 24 workdays = 12

days 6

where 8 = optimistic time, 10 = most likely time, and 24 = pessimistic time

PERT-Example

Activity Optimistic Most Likely Pessimistic

A 5 5 8

B 12 15 18

C 8 10 15

D 7 8 10

E 10 12 17

palestine university - gaza faculty of business and finance project scheduling techniques, defining...

Documents

project slide

project project charter

project finish

project time management

various project deliverables

time constraints

completed projects

schedule issues