scope and time management. intensive course on project management project scope management project...

Scope and Time Management

Intensive course on Project Management

Project Scope ManagementProject Scope Management Project DefinitionProject Definition

Key Inputs to Project Definition: Key Inputs to Project Definition: Clearly defined requirements Clearly defined requirements Defined mission and objectives of the project Defined mission and objectives of the project Defined and agreed statement of work Defined and agreed statement of work The objectives must be SMART The objectives must be SMART

Specific Specific Measurable Measurable Agreed to by the teams and stakeholder d Agreed to by the teams and stakeholder d Realistic within specific environment Realistic within specific environment Time bound Time bound

Key outputs of the project Definition: Key outputs of the project Definition: Project Charter Project Charter Project Stakeholder identification and Project Stakeholder identification and

assessment assessment Risk Identification, assessment and Risk Identification, assessment and

response response Quality plan Quality plan Communication plan Communication plan Work Breakdown structure Work Breakdown structure


Project Scope ManagementProject Scope Management The process involved in defining and controlling what is or The process involved in defining and controlling what is or

not included in the project.not included in the project.

This is the process necessary for developing a detailed project scope statement as the basis for future project decisions.

Five Key processes involved in the scope management. Initiation: The creation of project charter Scope Planning: Establishing Decision making criteria Scope definition: Creating Work Breakdown structure

Breaking major deliverables to smaller manageable components. Scope verification: Formal acceptance of scope definition by key

stake holders. Scope Change Control.

Project Selection Approaches Project Selection Approaches

The analytical Approaches: The analytical Approaches: Need Funding and Will ( NFW) ModelNeed Funding and Will ( NFW) Model

Do people agree to the project needs? Do people agree to the project needs? Is Organization ready to fund the project? Is Organization ready to fund the project? Is there a strong will to make a project success? Is there a strong will to make a project success?

Categorization Approaches: Categorization Approaches: Problems opportunities and Directive ( POD) Problems opportunities and Directive ( POD) Window of opportunity Window of opportunity Overall priority- High medium or Low? Overall priority- High medium or Low?

Financial Approaches: Financial Approaches: Net Present Value ( Time Value of Money) Net Present Value ( Time Value of Money)

Estimate the project cash inflows and outflows of a project.Estimate the project cash inflows and outflows of a project. Determine the appropriate discount rate Determine the appropriate discount rate Discount each cash inflow and outflow to present time Discount each cash inflow and outflow to present time Add together all discounted cash inflows and outflows.Add together all discounted cash inflows and outflows. Highest NPV project is selected.Highest NPV project is selected.

Return on Investment ( ROI) Return on Investment ( ROI) Income/InvestmentIncome/Investment NPV/Discounted cost NPV/Discounted cost Total discounted benefits-Total discounted Costs/disc costs Total discounted benefits-Total discounted Costs/disc costs

Pay back period: Pay back period: The amount of time needed before discounted benefits exceed the The amount of time needed before discounted benefits exceed the

cots cots When NPV turns positive When NPV turns positive How soon the investment starts paying off. How soon the investment starts paying off.


Weighted Scoring Model:Weighted Scoring Model: Identify selection criteria ( Time, priority, estimated pay backs) Identify selection criteria ( Time, priority, estimated pay backs) Assign weight to each criteriaAssign weight to each criteria Assign score to each criteriaAssign score to each criteria Calculate weighted score for each project Calculate weighted score for each project Project with highest score wins; Project with highest score wins; Some Project selection criterion are: Some Project selection criterion are:

Fit with mission Fit with mission Consistency with objectives Consistency with objectives Consistency with strategy Consistency with strategy Contribution to goals Contribution to goals Company ImageCompany Image ProfitabilityProfitability ROI ROI Customer satisfaction Customer satisfaction Corporate strength baseCorporate strength base Corporate weakness avoidanceCorporate weakness avoidance Risk level acceptability Risk level acceptability Policy guidelines consistency Policy guidelines consistency

Non Numeric/Qualitative Models:Non Numeric/Qualitative Models: Sacred Cow Sacred Cow Operating necessity Operating necessity Comparative necessity Comparative necessity Product line extension Product line extension Comparative benefit model Comparative benefit model

Project Charter Project Charter

A document that formally recognizes the A document that formally recognizes the existence of a project and provides direction existence of a project and provides direction on the project objectives and management .on the project objectives and management .

The project Charter at minimum must contain; The project Charter at minimum must contain; Title and authorization Title and authorization Name of Project Manager and contract info Name of Project Manager and contract info Statement of the project Statement of the project Summary of approachSummary of approach

Roles and responsibility matrix Roles and responsibility matrix Sign off package for key stakeholders Sign off package for key stakeholders

Scope Planning Scope Planning

This is the process necessary for creating a project scope management plan that documents how the project scope will be defined, verified and controlled, and how the work breakdown structure will be created and defined.

Scope Statement or Statement of work Scope Statement or Statement of work

The key document to confirm the scope of the project The key document to confirm the scope of the project which includes; which includes;

Project justificationProject justificationProject products Project products Summary of project deliverableSummary of project deliverableScope management plan ( CST)Scope management plan ( CST)Scope definition: Work break down structure Scope definition: Work break down structure

Scope Definition This is the process necessary for developing a

detailed project scope statement as the basis for future project decisions.


Work Breakdown Structure: WBS Work Breakdown Structure: WBS The project hierarchy of deliverables.The project hierarchy of deliverables. This is the process necessary for subdividing the major project This is the process necessary for subdividing the major project

deliverables and project work into smaller, more manageable deliverables and project work into smaller, more manageable components.components.

WBS supports the MBO ( Management By Objectives)WBS supports the MBO ( Management By Objectives) Begin with the project scope statementBegin with the project scope statement Task description developed ( Use a verb or noun)Task description developed ( Use a verb or noun) Develop WBS to the lowest level of control required to Develop WBS to the lowest level of control required to

effectively manage a product ( Work package effectively manage a product ( Work package = 80 hours) = 80 hours) Each work is developed to accomplish a discrete and separate Each work is developed to accomplish a discrete and separate

element of work element of work Assign package to single organizational unit for exclusive Assign package to single organizational unit for exclusive

responsibility responsibility Organize WBS by tasks Organize WBS by tasks

Phase Phase Task Task Activity Activity Step Or by deliverables Step Or by deliverables

Hardware Hardware Software Software NetworkingNetworking


Approaches to develop WBS Approaches to develop WBS Using guidelinesUsing guidelines

Government departments Government departments Bidding process comparison Bidding process comparison

The analogy approach The analogy approach Template of other projectsTemplate of other projects

The top down approachThe top down approach Starting from the largest and splitting it into smaller componentStarting from the largest and splitting it into smaller component From whole to parts From whole to parts Used by experienced project managers Used by experienced project managers

The bottom up approach The bottom up approach From parts to whole From parts to whole Used for entirely new system Used for entirely new system

Qualities of good WBS Qualities of good WBS

IndependentIndependent Identifiable Identifiable Integrate-ableIntegrate-able Measurable Measurable

Intnsive course on Project Management

Other kinds of breakdown structuresOther kinds of breakdown structures

Organizational Breakdown Structure (OBS). Provides a hierarchically organized depiction of the project organization arranged so that the work packages can be related to the performing organizational units.

Bill of Materials (BOM). Presents a hierarchical tabulation of the physical assemblies, subassemblies, and components needed to fabricate a manufactured product.

Risk Breakdown Structure (RBS). A hierarchically organized depiction of the identified project risks arranged by risk category.

Resource Breakdown Structure (RBS). A hierarchically organized depiction of the resources by type to be used on the project.

Scope Change Control Scope Change Control

Scope change is both costly and time Scope change is both costly and time consuming consuming

Scope Change can be controlled as Scope Change can be controlled as By Scope Change control By Scope Change control

Formal process for change in terms of cost time Formal process for change in terms of cost time and quality. and quality.

Scope Change Verification Scope Change Verification The process of documenting the project processes The process of documenting the project processes

and key stakeholders to sign off them.and key stakeholders to sign off them.

Minimizing scope ChangeMinimizing scope Change Develop and follow requirement management process Develop and follow requirement management process Use techniques such as JAD( Joint Application Design) Use techniques such as JAD( Joint Application Design)

session to gain thorough under standing of user session to gain thorough under standing of user requirements.( Developed by IBM) requirements.( Developed by IBM)

Put all requirements in writing and keep them current and Put all requirements in writing and keep them current and readily available.readily available.

Provide adequate testing through project life cycle. Provide adequate testing through project life cycle. Create formalized Change Control system and required Create formalized Change Control system and required

stakeholder sign off stakeholder sign off Stick to completion date. Stick to completion date.


Time Management Time Management The processes involved in timely completion of the project; The processes involved in timely completion of the project;

Activity definition: Activity definition: A task is an element of work that has an expected duration , cost and resource A task is an element of work that has an expected duration , cost and resource

requirement. requirement. A more detailed WBS A more detailed WBS

Activity sequencing: Activity sequencing: The order and dependencies of the activities and documenting these.The order and dependencies of the activities and documenting these. The dependencies are The dependencies are

Mandatory : One task cannot start unless the previous one finished Mandatory : One task cannot start unless the previous one finished Discretionary : Defined by the project team.Discretionary : Defined by the project team. External: Depending on project activity External: Depending on project activity

Activity duration estimation:Activity duration estimation: No of work period required to complete an activity No of work period required to complete an activity

Schedule development.Schedule development. Analyzing activity sequences, duration estimates and resource requirements to create Analyzing activity sequences, duration estimates and resource requirements to create

a workable schedule.a workable schedule.

Schedule Control : Schedule Control : Controlling and managing changes in the project schedulesControlling and managing changes in the project schedules

Activity Definition

This is the process necessary for identifying the specific activities that need to be performed to produce the various project deliverables.

Activity Sequencing

This is the process necessary for identifying and documenting dependencies among scheduled activities.

Activity Resource Estimating

This is the process necessary for estimating the type and quantities of resources required to perform each schedule

activity.

Activity Resource Estimation Activity Resource Estimation

1. Expert JudgmentExpert JudgmentExpert judgment is often required to assess the resource-related inputs Expert judgment is often required to assess the resource-related inputs to this process. Any group or person with specialized knowledge in to this process. Any group or person with specialized knowledge in resource planning and estimating can provide such expertise.resource planning and estimating can provide such expertise.

2 Alternatives Analysis2 Alternatives AnalysisMany schedule activities have alternative methods of accomplishment. Many schedule activities have alternative methods of accomplishment. They include using various levels of resource capability or skills, They include using various levels of resource capability or skills, different size or type of machines, different tools (hand versus different size or type of machines, different tools (hand versus automated), and make-or-buy decisions regarding the resourceautomated), and make-or-buy decisions regarding the resource

3 Published Estimating Data3 Published Estimating DataSeveral companies routinely publish updated production rates and unit Several companies routinely publish updated production rates and unit costs of resources for an extensive array of labor trades, materiel, and costs of resources for an extensive array of labor trades, materiel, and equipment for different countries and geographical locations within equipment for different countries and geographical locations within countries.countries.

4 Project Management SoftwareProject Management SoftwareProject management software has the capability to help plan, organize, Project management software has the capability to help plan, organize, and manage resource pools and develop resource estimates. and manage resource pools and develop resource estimates. Depending upon the sophistication of the software, resource breakdown Depending upon the sophistication of the software, resource breakdown structures, resource availabilities, and resource rates can be defined, structures, resource availabilities, and resource rates can be defined, as well as various resource calendars.as well as various resource calendars.

5 Bottom-up Estimating5 Bottom-up EstimatingWhen a schedule activity cannot be estimated with a reasonable When a schedule activity cannot be estimated with a reasonable degree of confidence, the work within the schedule activity is degree of confidence, the work within the schedule activity is decomposed into more detail. The resource needs of each lower, more decomposed into more detail. The resource needs of each lower, more detailed piece of work are estimated, and these estimates are then detailed piece of work are estimated, and these estimates are then aggregated into a total quantity for each of the schedule activity’s aggregated into a total quantity for each of the schedule activity’s resources. Schedule activities may or may not have dependencies resources. Schedule activities may or may not have dependencies between them that can affect the application and use of resources. If between them that can affect the application and use of resources. If there are dependencies, this pattern of resource usage is reflected in there are dependencies, this pattern of resource usage is reflected in the estimated requirements of the schedule activity and is documented.the estimated requirements of the schedule activity and is documented.


Activity Duration Estimating This is the process necessary for estimating the number of work periods

that will be needed to complete individual schedule activities.


Activity Estimation Techniques Activity Estimation Techniques 1. Expert Judgment Activity durations are often difficult to estimate because of the number of factors

that can influence them, such as resource levels or resource productivity. Expert judgment, guided by historical information, can be used whenever possible.

2 Analogous Estimating Analogous duration estimating means using the actual duration of a previous

similar schedule activity as the basis for estimating the duration of a future schedule activity. Analogous duration estimating is most reliable when the previous activities are similar in fact and not just in appearance, and the project team members preparing the estimates have the needed expertise.

3 Parametric Estimating Estimating the basis for activity durations can be quantitatively determined by

multiplying the quantity of work to be performed by the productivity rate. For example, productivity rates can be estimated on a design project by the number of drawings times labor hours per drawing, or a cable installation in meters of cable times labor hours per meter. The total resource quantities are multiplied by the labor hours per work period or the production capability per work period, and divided by the number of those resources being applied to determine activity duration in work periods.

. 4 Three-Point Estimates The accuracy of the activity duration estimate can be improved by

considering the amount of risk in the original estimate. Three-point estimates are based on determining three types of estimates:

Most likely. The duration of the schedule activity, given the resources likely to be assigned, their productivity, realistic expectations of availability for the schedule activity, dependencies on other participants, and interruptions.

Optimistic. The activity duration is based on a best-case scenario of what is described in the most likely estimate.

Pessimistic. The activity duration is based on a worst-case scenario of what is described in the most likely estimate.

An activity duration estimate can be constructed by using an average of the three estimated durations. That average will often provide a more accurate activity duration estimate than the single point, most-likely estimate.

Schedule Development

This is the process necessary for analyzing activity sequences, durations, resource requirements, and schedule constraints to create the project schedule.

Schedule Development tools Schedule Development tools Network diagrams: Network diagrams:

A systematic display of the logical relationship between project activities or the A systematic display of the logical relationship between project activities or the sequencing of project activities. Three approaches; sequencing of project activities. Three approaches;

Activity on Nodes ( AON) or Precedence Diagram method ( PDM). Activity on Nodes ( AON) or Precedence Diagram method ( PDM).

PDM includes four types of dependencies or precedence relationships:PDM includes four types of dependencies or precedence relationships:

Finish-to-Start. The initiation of the successor activity depends upon the Finish-to-Start. The initiation of the successor activity depends upon the completion of the predecessor activity.completion of the predecessor activity.

Finish-to-Finish. The completion of the successor activity depends upon the Finish-to-Finish. The completion of the successor activity depends upon the completion of the predecessor activity.completion of the predecessor activity.

Start-to-Start. The initiation of the successor activity depends upon theStart-to-Start. The initiation of the successor activity depends upon the initiation of the predecessor activity.initiation of the predecessor activity.

Start-to-Finish. The completion of the successor activity depends upon theStart-to-Finish. The completion of the successor activity depends upon the initiation of the predecessor activity.initiation of the predecessor activity.

In PDM, finish-to-start is the most commonly used type of precedenceIn PDM, finish-to-start is the most commonly used type of precedence relationship. Start-to-finish relationships are rarely used.relationship. Start-to-finish relationships are rarely used.

Precedence Diagram Precedence Diagram

Arrow Diagramming Method (ADM)

ADM is a method of constructing a project schedule network diagram that uses arrows to represent activities and connects them at nodes to show their dependencies.

This technique is also called activity-on-arrow (AOA) and, although less prevalent than PDM, it is still used in teaching schedule network theory and in some application areas.

ADM uses only finish-to-start dependencies and can require the use of “dummy” relationships called dummy activities, which are shown as dashed lines, to define all logical relationships correctly. Since dummy activities are not actual schedule activities (they have no work content), they are given a zero value duration for schedule network analysis purposes.

Schedule Network Templates

Standardized project schedule network diagram templates can be used to expedite the preparation of networks of project schedule activities. They can include an entire project or only a portion of it.

Portions of a project schedule network diagram are often referred to as a sub network or a fragment network. Sub network templates are especially useful when a project includes several identical or nearly identical deliverables, such as floors on a high-rise office building, clinical trials on a pharmaceutical research project, coding program modules on a software project, or the start-up phase of a development project.

Cost Estimating

This is the process necessary for developing an approximation of the costs of the resources needed to complete project activities.


Schedule Development TechniquesSchedule Development Techniques

1 Schedule Network Analysis

Schedule network analysis is a technique that generates the project schedule. critical path method, critical chain method, what-if analysis, and resource leveling to calculate the early and late start and finish dates,

and scheduled start and finish dates for the uncompleted portions of project schedule activities.

2 Critical Path Method The critical path method is a schedule network analysis technique that is

performed using the schedule model. Calculates the theoretical early start and finish dates, and late start and

finish dates, for all schedule by performing a forward pass analysis and a backward pass analysis through the project schedule

Calculated early start and finish dates, and late start and finish dates, may or may not be the same on any network path since total float, which provides schedule flexibility, may be positive, negative, or zero.

On any network path, the schedule flexibility is measured by the positive difference between early and late dates, and is termed “total float.”

Critical paths have either a zero or negative total float, and schedule activities on a critical path are called “critical activities.”

Adjustments to activity durations, logical relationships, leads and lags, or other schedule constraints may be necessary to produce network paths with a zero or positive total float. Once the total float for a network path is zero or positive, then the free float — the amount of time that a schedule activity can be delayed without delaying the early start date of any immediate successor activity within the network path — can also be determined.


3 Schedule Compression Schedule compression shortens the project schedule without changing

the project scope, to meet schedule constraints, imposed dates, or other schedule objectives.

Schedule compression techniques include:

Crashing. Schedule compression technique in which cost and schedule tradeoffs are

analyzed to determine how to obtain the greatest amount of compression for the least incremental cost. Crashing does not always produce a viable alternative and can result in increased cost.

Fast tracking. A schedule compression technique in which phases or activities that

normally would be done in sequence are performed in parallel.An example would be to construct the foundation for a building before all the architectural drawings are complete. Fast tracking can result in rework and increased risk. This approach can require work to be performed without completed detailed information, such as engineering drawings. It results in trading cost for time, and increases the risk of achieving the shortened project schedule.

4. What-If Scenario Analysis

This is an analysis of the question “What if the situation represented by scenario ‘X’ happens?” A schedule network analysis is performed using the schedule model to compute the different scenarios, such as delaying a major component delivery, extending specific engineering durations, or introducing external factors, such as a strike or a change in the permitting process. The outcome of the what-if scenario analysis can be used to assess the feasibility of the project schedule under adverse conditions, and in preparing contingency and response plans to overcome or mitigate the impact of unexpected situations.

Simulation involves calculating multiple project durations with different sets of activity assumptions. The most common technique is Monte Carlo Analysis in which a distribution of possible activity durations is defined for each schedule activity and used to calculate a distribution of possible outcomes for the total project.

5. Resource Leveling Resource leveling is a schedule network analysis technique applied to a

schedule model that has already been analyzed by the critical path method. Resource leveling is used to address schedule activities that need to be performed to meet specified delivery dates, to address the situation where shared or critical required resources are only available at certain times or are only available in limited quantities, or to keep selected resource usage at a constant level during specific time periods of the project work. This resource usage leveling approach can cause the original critical path to change.


6 Critical Chain Method Critical chain is another schedule network analysis technique that

modifies the project schedule to account for limited resources.

Critical chain combines deterministic and probabilistic approaches.

The critical path is then calculated. After the critical path is identified, resource availability is entered and the resource-limited schedule result is determined. The resulting schedule often has an altered critical path.

The critical chain method adds duration buffers that are non-work schedule activities to maintain focus on the planned activity durations. Once the buffer schedule activities are determined, the planned activities are scheduled to their latest possible planned start and finish dates. Consequently, in lieu of managing the total float of network paths, the critical chain method focuses on managing the buffer activity durations and the resources applied to planned schedule activities

7 Project Management SoftwareProject management scheduling software is widely used to assist with schedule development. Other software might be capable of interacting directly or indirectly with project management software to carry out the requirements of other Knowledge Areas, such as cost estimating by time period.

8. Applying CalendarsProject calendars) and resource calendars identify periods when work is allowed. Project calendars affect all activities. For example, it may not be possible to work on the site during certain periods of the year because of weather. Resource calendars affect a specific resource or category of resources. Resource calendars reflect how some resources work only during normal business hours, while others work three full shifts, or a project team member might be unavailable, such as on vacation or in a training program, or a labor contract can limit certain workers to certain days of the week.

9 Adjusting Leads and LagsSince the improper use of leads or lags can distort the project schedule, the leads or lags are adjusted during schedule network analysis to develop a viable project schedule.

10 Schedule ModelSchedule data and information are compiled into the schedule model for the project. The schedule model tool and the supporting schedule model data are used in conjunction with manual methods or project management software to perform schedule network analysis to generate the project schedule.

Schedule Development: Outputs Project Schedule The project schedule includes at least a planned start date and planned

finish date for each schedule activity.

A project target schedule may also be developed with defined target start dates and target finish dates for each schedule activity.

The project schedule can be presented in summary form, sometimes referred to as the master schedule or milestone schedule, or presented in detail.

Project schedule network diagrams.

These diagrams, with activity date information, usually show both the project network logic and the project’s critical path schedule activities. These diagrams can be presented in the activity-on-node diagram format, or presented in a time-scaled schedule network diagram format that is sometimes called a logic bar chart,

Bar charts. These charts, with bars representing activities, show

activity start and end dates, as well as expected durations. Bar charts are relatively easy to read, and are frequently used in management presentations.

Milestone charts. These charts are similar to bar charts, but only identify

the scheduled start or completion of major deliverables and key external interfaces.

Graph or bar chart with a bar for each project activity that shows passage of time

Provides visual display of project scheduleProvides visual display of project schedule

Gantt Chart

Schedule Control Schedule Control Schedule control is concerned with:

Determining the current status of the project schedule Influencing the factors that create schedule changes Determining that the project schedule has changed Managing the actual changes as they occur.

PERT PERT ( Program Evaluation and Review ( Program Evaluation and Review Technique)Technique) A network analysis technique used to A network analysis technique used to

estimate project duration when there is high estimate project duration when there is high degree of uncertainty about the individual degree of uncertainty about the individual duration estimates.duration estimates.

PERT weighted average of activity time PERT weighted average of activity time (Optimistic time + 4 times most likely time + Pessimistic time)/6(Optimistic time + 4 times most likely time + Pessimistic time)/6

Controlling Changes to Project ScheduleControlling Changes to Project Schedule

Make realistic and workable schedule.Make realistic and workable schedule. Regular Progress Review meetings.Regular Progress Review meetings. Key leadership skills for schedule control Key leadership skills for schedule control

are are Empowerment Empowerment Incentives Incentives Discipline Discipline Negotiation Negotiation

History of CPM/PERTHistory of CPM/PERT

Critical Path Method (CPM)Critical Path Method (CPM) E I Du Pont de Nemours & Co. (1957) for construction of E I Du Pont de Nemours & Co. (1957) for construction of

new chemical plant and maintenance shut-downnew chemical plant and maintenance shut-down Deterministic task timesDeterministic task times Activity-on-node network constructionActivity-on-node network construction Repetitive nature of jobsRepetitive nature of jobs

Project Evaluation and Review Technique (PERT)Project Evaluation and Review Technique (PERT) U S Navy (1958) for the POLARIS missile programU S Navy (1958) for the POLARIS missile program Multiple task time estimates (probabilistic nature)Multiple task time estimates (probabilistic nature) Activity-on-arrow network constructionActivity-on-arrow network construction Non-repetitive jobs (R & D work)Non-repetitive jobs (R & D work)

Network exampleNetwork 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 ?

CPM calculationCPM calculation

PathPath A connected sequence of activities leading A connected sequence of activities leading

from the starting event to the ending eventfrom the starting event to the ending event

Critical PathCritical Path The longest path (time); determines the project The longest path (time); determines the project

durationduration

Critical ActivitiesCritical Activities All of the activities that make up the critical pathAll of the activities that make up the critical path

Forward PassForward Pass Earliest Start Time (ES)Earliest Start Time (ES)

earliest time an activity can start earliest time an activity can start ES = maximum EF of immediate predecessorsES = maximum EF of immediate predecessors

Earliest finish time (EF)Earliest finish time (EF) earliest time an activity can finishearliest time an activity can finish earliest start time plus activity timeearliest start time plus activity time

EF= ES + EF= ES + tt

Latest Start Time (LS)

Latest time an activity can start without delaying critical path time

LS= LF - t

Latest finish time (LF)

latest time an activity can be completed without delaying critical path time

LS = minimum LS of immediate predecessors

Backward Pass

CPM analysisCPM analysis Draw the CPM networkDraw the CPM network Analyze the paths through the networkAnalyze the paths through the network Determine the float for each activityDetermine the float for each activity

Compute the activity’s floatCompute the activity’s float

float = LS - ES = LF - EFfloat = LS - ES = LF - EF Float is the maximum amount of time that this activity can Float is the maximum amount of time that this activity can

be delay in its completion before it becomes a critical be delay in its completion before it becomes a critical activity, i.e., delays completion of the projectactivity, i.e., delays completion of the project

Find the critical path is that the sequence of activities and Find the critical path is that the sequence of activities and events where there is no “slack” i.e.. events where there is no “slack” i.e.. Zero slackZero slack Longest path through a networkLongest path through a network

Find the project duration is minimum project completion timeFind the project duration is minimum project completion time

CPM Example: CPM Example: CPM NetworkCPM Network

a, 6a, 6a, 6a, 6

f, 15f, 15f, 15f, 15

b, 8b, 8b, 8b, 8

c, 5c, 5c, 5c, 5e, 9e, 9e, 9e, 9

d, 13d, 13d, 13d, 13

g, 17g, 17g, 17g, 17 h, 9h, 9h, 9h, 9

i, 6i, 6i, 6i, 6

j, 12j, 12j, 12j, 12

CPM ExampleCPM Example ES and EF TimesES and EF Times

a, 6a, 6a, 6a, 6

f, 15f, 15f, 15f, 15

b, 8b, 8b, 8b, 8

c, 5c, 5c, 5c, 5

e, 9e, 9e, 9e, 9

d, 13d, 13d, 13d, 13

g, 17g, 17g, 17g, 17 h, 9h, 9h, 9h, 9

i, 6i, 6i, 6i, 6

j, 12j, 12j, 12j, 12

0 6

0 8

0 5


CPM ExampleCPM Example

ES and EF TimesES and EF Times

a, 6a, 6a, 6a, 6

f, 15f, 15f, 15f, 15

b, 8b, 8b, 8b, 8

c, 5c, 5c, 5c, 5

e, 9e, 9e, 9e, 9

d, 13d, 13d, 13d, 13

g, 17g, 17g, 17g, 17 h, 9h, 9h, 9h, 9

i, 6i, 6i, 6i, 6

j, 12j, 12j, 12j, 12

0 6

0 8

0 5

5 14

8 21

6 23

6 21


ES and EF TimesES and EF Times

a, 6a, 6a, 6a, 6

f, 15f, 15f, 15f, 15

b, 8b, 8b, 8b, 8

c, 5c, 5c, 5c, 5

e, 9e, 9e, 9e, 9

d, 13d, 13d, 13d, 13

g, 17g, 17g, 17g, 17 h, 9h, 9h, 9h, 9

i, 6i, 6i, 6i, 6

j, 12j, 12j, 12j, 12

0 6

0 8

0 5

5 14

8 21 21 33

6 23 21 30

23 29

6 21

Project’s EF = 33Project’s EF = 33


LS and LF TimesLS and LF Times

a, 6a, 6a, 6a, 6

f, 15f, 15f, 15f, 15

b, 8b, 8b, 8b, 8

c, 5c, 5c, 5c, 5

e, 9e, 9e, 9e, 9

d, 13d, 13d, 13d, 13

g, 17g, 17g, 17g, 17

h, 9h, 9h, 9h, 9

i, 6i, 6i, 6i, 6

j, 12j, 12j, 12j, 12

0 6

0 8

0 5

5 14

8 21 21 33

6 23

21 30

23 29

6 21

21 33

27 33

24 33

CPM ExampleCPM ExampleCPM ExampleCPM Example

LS and LF TimesLS and LF Times

a, 6a, 6a, 6a, 6

f, 15f, 15f, 15f, 15

b, 8b, 8b, 8b, 8

c, 5c, 5c, 5c, 5

e, 9e, 9e, 9e, 9

d, 13d, 13d, 13d, 13

g, 17g, 17g, 17g, 17

h, 9h, 9h, 9h, 9

i, 6i, 6i, 6i, 6

j, 12j, 12j, 12j, 12

0 6

0 8

0 5

5 14

8 21 21 33

6 23

21 30

23 29

6 21

4 10

0 8

7 12

12 21

21 33

27 33

8 21

10 27

24 33

18 24


CPM ExampleCPM ExampleCPM ExampleCPM Example

FloatFloat

a, 6a, 6a, 6a, 6

f, 15f, 15f, 15f, 15

b, 8b, 8b, 8b, 8

c, 5c, 5c, 5c, 5e, 9e, 9e, 9e, 9

d, 13d, 13d, 13d, 13

g, 17g, 17g, 17g, 17

h, 9h, 9h, 9h, 9

i, 6i, 6i, 6i, 6

j, 12j, 12j, 12j, 12

0 6

0 8

0 5 5 14

8 21 21 33

6 23

21 30

23 29

6 21

3 9

0 8

7 12 12 21

21 33

27 33

8 21

10 27

24 33

9 24

3 4

3

3

4

0

0

7 7

0

CPM ExampleCPM Example Critical PathCritical Path

a, 6a, 6a, 6a, 6

f, 15f, 15f, 15f, 15

b, 8b, 8b, 8b, 8

c, 5c, 5c, 5c, 5

e, 9e, 9e, 9e, 9

d, 13d, 13d, 13d, 13

g, 17g, 17g, 17g, 17 h, 9h, 9h, 9h, 9

i, 6i, 6i, 6i, 6

j, 12j, 12j, 12j, 12


PERT PERT PERT is based on the assumption that an activity’s duration PERT is based on the assumption that an activity’s duration

follows a probability distribution instead of being a single follows a probability distribution instead of being a single valuevalue

Three time estimates are required to compute the Three time estimates are required to compute the parameters of an activity’s duration distribution:parameters of an activity’s duration distribution: pessimistic timepessimistic time (t (tp p ) - the time the activity would take if ) - the time the activity would take if

things did not go wellthings did not go well most likely timemost likely time (t (tm m ) - the consensus best estimate of the ) - the consensus best estimate of the

activity’s durationactivity’s duration optimistic timeoptimistic time (t (to o ) - the time the activity would take if ) - the time the activity would take if

things did go wellthings did go well

Mean (expected time): te =tp + 4 tm + to

6

Variance: Vt =2 =tp - to

6

2

PERT analysisPERT analysis Draw the network.Draw the network. Analyze the paths through the network and find the critical Analyze the paths through the network and find the critical

path.path. The length of the critical path is the mean of the project The length of the critical path is the mean of the project

duration probability distribution which is assumed to be duration probability distribution which is assumed to be normalnormal

The standard deviation of the project duration probability The standard deviation of the project duration probability distribution is computed by adding the variances of the critical distribution is computed by adding the variances of the critical activities (all of the activities that make up the critical path) activities (all of the activities that make up the critical path) and taking the square root of that sumand taking the square root of that sum

Probability computations can now be made using the normal Probability computations can now be made using the normal distribution table.distribution table.

Probability computationProbability computation

Determine probability that project is completed within specified time

Z = x -

where = tp = project mean time

= project standard mean time

x = (proposed ) specified time

Normal Distribution of Project TimeNormal Distribution of Project Time

= tp Timex

Z

Probability

PERT Example PERT Example

Immed. Optimistic Most Likely Immed. Optimistic Most Likely PessimisticPessimistic

ActivityActivity Predec.Predec. Time (Hr.Time (Hr.) ) Time (Hr.)Time (Hr.) Time (Hr.)Time (Hr.)

A -- 4 6 8A -- 4 6 8B -- 1 4.5 5B -- 1 4.5 5C A 3 3 3C A 3 3 3

D A 4 5 6 D A 4 5 6 E A 0.5 1 1.5E A 0.5 1 1.5 F B,C 3 4 5F B,C 3 4 5 G B,C 1 1.5 5G B,C 1 1.5 5 H E,F 5 6 7H E,F 5 6 7 I E,F 2 5 8I E,F 2 5 8 J D,H 2.5 2.75 4.5J D,H 2.5 2.75 4.5 K G,I 3 5 7K G,I 3 5 7

PERT ExamplePERT Example

AA

DD

CC

BBFF

EE

GG

II

HH

KK

JJ

PERT Network

PERT ExamplePERT Example ActivityActivity Expected TimeExpected Time VarianceVariance A A 6 6 4/9 4/9

B B 4 4 4/9 4/9 C C 3 3 0 0 D D 5 5 1/9 1/9 E E 1 1 1/36 1/36 F F 4 4 1/9 1/9 G G 2 2 4/9 4/9 H H 6 6 1/9 1/9 I I 5 5 1 1 J J 3 3 1/9 1/9 K K 5 5 4/9 4/9


ActivityActivity ESES EFEF LSLS LFLF SlackSlack A 0 A 0 6 6 0 0 6 6 0 *critical0 *critical

B 0 B 0 4 4 5 5 9 5 9 5 C 6 C 6 9 9 6 6 9 9 0 *0 *

D 6 D 6 11 11 15 15 20 20 99 E 6 E 6 7 7 12 12 13 13 66 F 9 F 9 13 13 9 9 13 13 0 *0 * G 9 G 9 11 11 16 16 18 18 77 H H 13 13 19 19 14 14 20 20 11 I I 13 13 18 18 13 13 18 18 0 *0 * J J 19 19 22 22 20 20 23 23 11 K K 18 18 23 23 18 18 23 23 0 *0 *


VVpathpath = V = VAA + V + VCC + V + VFF + V + VII + V + VKK

= 4/9 + 0 + 1/9 + 1 + 4/9 = 4/9 + 0 + 1/9 + 1 + 4/9

= 2= 2

pathpath = 1.414 = 1.414

zz = (24 - 23)/ = (24 - 23)/(24-23)/1.414 (24-23)/1.414 = .71= .71

From the Standard Normal Distribution From the Standard Normal Distribution table: table:

P(z P(z << .71) = .5 + .2612 = .7612 .71) = .5 + .2612 = .7612

Benefits of CPM/PERTBenefits of CPM/PERT Useful at many stages of project managementUseful at many stages of project management Mathematically simpleMathematically simple Give critical path and slack timeGive critical path and slack time Provide project documentationProvide project documentation Useful in monitoring costsUseful in monitoring costs

•How long will the entire project take to be completed? What are the risks involved? •Which are the critical activities or tasks in the project which could delay the entire project if they were not completed on time? •Is the project on schedule, behind schedule or ahead of schedule? •If the project has to be finished earlier than planned, what is the best way to do this at the least cost?

CPM/PERT can answer the following important questions:

Limitations to CPM/PERTLimitations to CPM/PERT Clearly defined, independent and stable activitiesClearly defined, independent and stable activities Specified precedence relationshipsSpecified precedence relationships Over emphasis on critical pathsOver emphasis on critical paths Deterministic CPM modelDeterministic CPM model Activity time estimates are subjective and depend on Activity time estimates are subjective and depend on

judgmentjudgment PERT assumes a beta distribution for these time estimates, PERT assumes a beta distribution for these time estimates,

but the actual distribution may be differentbut the actual distribution may be different PERT consistently underestimates the expected project PERT consistently underestimates the expected project

completion time due to alternate paths becoming criticalcompletion time due to alternate paths becoming critical

To overcome the limitation, Monte Carlo simulations can be performed on the network to eliminate the optimistic bias

Computer Software Computer Software for Project Managementfor Project Management

Microsoft Project Microsoft Project (Microsoft Corp.) (Microsoft Corp.) MacProjectMacProject (Claris Corp.) (Claris Corp.) PowerProjectPowerProject (ASTA Development Inc.) (ASTA Development Inc.) Primavera Project PlannerPrimavera Project Planner (Primavera) (Primavera) Project SchedulerProject Scheduler (Scitor Corp.) (Scitor Corp.) Project WorkbenchProject Workbench (ABT Corp.) (ABT Corp.)

scope and time management. intensive course on project management project scope management project...

Documents

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project manager

project needs

project success

project cash inflows

highest npv project

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