unit 4: time management pmbok guide, chapter 6) · (pmbok® guide, chapter 6) ... 6.1 plan schedule...

© CMF Solutions and ESI July 2013 PMC:DJ4:EN:000 ver.2.0 4-1

Unit 4: Time Management (PMBOK® Guide, Chapter 6)

The questions on this topic focus heavily on scheduling techniques, network diagrams, Gantt charts, the critical path, compressing the schedule, PERT, and float. You may or may not have to actually work a network diagram, but you will be expected to answer fundamental questions about the critical path, float, crashing a project schedule, and dealing with various dependencies such as finish-to-finish or start-to-start. See course slide #4-1 for an overview of time management.

Major Processes 6.1 Plan Schedule Management (establishing procedures for planning, developing,

managing, executing, and controlling the schedule) 6.2 Define Activities (identifying specific activities to be accomplished) 6.3 Sequence Activities (identifying and documenting relationships among activities) 6.4 Estimate Activity Resources (estimating type and quantity of resources needed)6.5 Estimate Activity Durations (approximating the number of work periods to

complete individual activities with estimated resources) 6.6 Develop Schedule (analyzing sequences, durations, resource requirements, and

schedule constraints to create the schedule) 6.7 Control Schedule (monitoring the status of the project to update progress and

managing changes to the schedule baseline)

PMI indicates that defining and sequencing activities, estimating resources and durations, and development of the schedule are discrete but tightly linked steps in building a project schedule. On some projects, especially smaller ones, these discrete steps are viewed and performed as a single process.

6.1 Plan Schedule Management (PMBOK® Guide, p. 145)

Plan Schedule Management establishes and documents procedures for planning, developing, managing, executing, and controlling the project schedule.

Plan Schedule Management

Inputs Tools Outputs

1. Project management plan 2. Project charter 3. Enterprise environmental factors 4. Organizational process assets

1. Expert judgment 2. Analytical techniques 3. Meetings

1. Schedule management plan

Unit 4: Time Management

4-2 PMC:DJ4:EN:000 ver.2.0 © CMF Solutions and ESI July 2013

Four Key Inputs for Plan Schedule Management (PMBOK® Guide, p. 146):

1. Project Management Plan: Information used explicitly at this step may include:

• Scope baseline: The scope statement and WBS information may be used for defining activities, estimating durations, and managing the schedule.

• Other information: Cost and risk information may be helpful in developing the schedule.

2. Project Charter: The charter usually contains a high-level, summary milestone schedule that would provide a starting point in thinking about the detailed schedule.

3. Enterprise Environmental Factors: Factors that influence the schedule management planning process may include:

• Organizational structure and resource availability

• Project management software and published commercial data

• Work authorization systems

4. Organizational Process Assets: The specific organizational process assets that may affect Plan Schedule Management include (PMBOK® Guide, p. 147):

• Lessons learned, historical information, and templates

• Schedule and change control procedures

• Monitoring and reporting tools

• Risk control procedures and project closure guidelines

Three Key Tools for Plan Schedule Management (PMBOK® Guide, p. 147):

1. Expert Judgment: Expert judgment coupled with historical information may help apply relevant information from similar projects.

2. Analytical Techniques: Various analytical techniques may help in choosing appropriate scheduling methodologies, estimating approaches, project management software, and whether to employ fast tracking and/or crashing.



3. Meetings: Used to help develop the schedule management plan.

One Key Output for Plan Schedule Management (PMBOK® Guide, p. 148):

1. Schedule Management Plan: A component of the project management plan that establishes the criteria and activities for developing, monitoring, and controlling the schedule. The schedule management plan may establish the following:

• Project schedule model development: The appropriate scheduling methodology and tool may be specified.

• Level of accuracy: The acceptable range of accuracy for duration estimates (may also include recommended amounts for contingency).

• Units of measure: The unit of measure for tracking key resources and time might be hours, days, weeks, or months of effort. The unit of measure for materials might be liters, tons, or cubic yards and so on.

• Organizational procedures links: The WBS provides a consistent framework for estimating schedules.

• Project schedule model maintenance: Processes used to update schedule status during execution of the work.

• Control thresholds: Establishes an allowable amount of variation before corrective action is triggered. Often expressed as a percentage of deviation.

• Rules of performance measurement: Earned Value rules for calculating how much credit to take for partially completed activities (e.g., 0-100, 50-50, and so on). These rules are described in the cost management chapter as part of the earned value management topic.

• Reporting formats: Formats and frequency for schedule status reports.

• Process descriptions: Schedule management processes are documented.

6.2 Define Activities (PMBOK® Guide, p. 149)

Activity definition involves identifying and documenting the specific activities that must be performed to produce the deliverables identified by the WBS. Activities are planned down to the work package level, which is the lowest level displayed in the WBS. PMI also says that work packages may be decomposed another level, which is designated as activities or schedule activities.



Define Activities


1. Schedule management plan 2. Scope baseline 3. Enterprise environmental factors 4. Organizational process assets

1. Decomposition 2. Rolling wave planning 3. Expert judgment

1. Activity list 2. Activity attributes 3. Milestone list

Four Key Inputs for Define Activities (PMBOK® Guide, p. 150):

1. Schedule Management Plan: Provides the level of detail necessary for managing the work.

2. Scope Baseline: The information explicitly used at this step includes the WBS, project deliverables, constraints, and assumptions.

3. Enterprise Environmental Factors (EEF): The relevant EEF items at this point may include:

• Organizational structure

• Published information from commercial databases

• Project management information systems

4. Organizational Process Assets: The specific organizational process assets that may affect defining project activities include (PMBOK® Guide, p. 151):

• Formal and informal activity planning procedures and guidelines

• Lessons learned knowledge base and historical information (activity lists from previous, similar projects)

• Standardized processes and templates

Three Key Tools for Define Activities (PMBOK® Guide, p. 151):

1. Decomposition: Subdividing project activities into smaller components. The lowest level shown in the WBS is the work package; however, work packages can be further decomposed into “activities,” which represent the work required to produce the work package deliverables. PMI indicates that a complete activity



list includes all the activities necessary to complete each work package.Involving team members in the decomposition may lead to more accurate results.

2. Rolling Wave Planning: A form of progressive elaboration where work to be performed in the near term is planned at a low level of the WBS (work package), i.e., a highly detailed plan with as much accuracy as possible. Work farther in the future is planned with less detail (at a higher level of the WBS, perhaps what some practitioners call a planning package). Course slide #4-2 shows what this timing distinction might look like.

3. Expert Judgment: Using appropriate subject matter experts to ensure the activity definition is accurate.

Three Key Outputs for Define Activities (PMBOK® Guide, p. 152):

1. Activity List: A comprehensive list of all activities that must be performed.The list should include all activities (including those decomposed below the work package level), an activity identifier (code of accounts number), and a sufficient description of the work.

2. Activity Attributes: Much like the WBS dictionary, activity attributes include detailed information for each activity. The amount of information increases as the project progresses (progressive elaboration). Activity attributes includes the following information:

• Activity ID, WBS ID, and activity name • Activity description • Predecessor and successor activities (for sequencing) • Logical relationships (type of dependency) • Leads and lags • Resource requirements • Imposed dates, constraints, and assumptions • Responsible resource • Geographical area (if work is done in multiple locations)

3. Milestone List: Milestones are important points in time and they have zero duration. Milestones may be requested or demanded by the customer, management, the team, or may be required by the contract. Typical milestones often include the date on which important activities should begin or end.



6.3 Sequence Activities (PMBOK® Guide, p. 153)

Activity sequencing involves identifying and documenting interactivity dependencies (also called logical relationships). The process can be done manually, with software, or with a combination of both. Except for the first and last, all activities must have a predecessor and a successor. In addition to appropriate logical relationships, it may be necessary to incorporate leads or lags to create realistic, achievable schedules.

Sequence Activities


1. Schedule management plan 2. Activity list 3. Activity attributes 4. Milestone list 5. Project scope statement 6. Enterprise environmental factors 7. Organizational process assets

1. Precedence diagramming method (PDM)

2. Dependency determination 3. Leads and lags

1. Project schedule network diagrams

2. Project documents updates

Seven Key Inputs for Sequence Activities (PMBOK® Guide, p. 154):

1. Schedule Management Plan: Identifies the intended scheduling method for the project.

2. Activity List: Identifies schedule activities that must be sequenced, Section 6.2.3.1.

3. Activity Attributes: An output of the previous process, Section 6.2.3.2. This information includes predecessors and successors for each activity.

4. Milestone List: Described in Section 6.2.3.3, milestones must also be sequenced and some milestones may have imposed dates (schedule constraints) that may affect sequencing.

5. Project Scope Statement: Includes product characteristics that help planners understand required activity sequences. For instance, there may be physical or technical aspects of the work that make a mandatory dependencynecessary. The scope statement also identifies deliverables, constraints, and assumptions which may influence sequencing decisions.



6. Enterprise Environmental Factors (EEF): EEF that may influence sequencing include:

• Government or industry standards

• Project management information system

• Scheduling tool and work authorization systems

7. Organizational Process Assets (OPA): The specific OPA that may affect the sequencing of project activities include (PMBOK® Guide, p. 156):

• Files from the knowledge base on scheduling methods

• Scheduling templates

Three Key Tools for Sequence Activities (PMBOK® Guide, p. 156):

1. Precedence Diagramming Method (PDM): This is one way to display a schedule in network fashion; it is also called activity-on-node. It was developed in the early 1960s at Stanford University and is the method that project management software uses today. The activities are listed inside boxes (called nodes) and are connected by lines (or arrows) to indicate sequences.

The PDM approach uses the following four types of dependencies:

• Finish-to-Start: Initiation of the successor activity depends on completion of the predecessor activity.

• Finish-to-Finish: Completion of the successor activity depends on completion of the predecessor activity.

• Start-to-Start: Initiation of the successor activity depends on initiation of the predecessor activity.

• Start-to-Finish: Completion of the successor activity depends on initiation of the predecessor activity.

Supplemental course slides #SU-3 through #SU-6 show examples of each type of dependency (use of the slides is optional).

Finish-to-start is the most commonly used dependency, whereas PMI suggests that start-to-finish is rarely used on actual projects.

Design Test Produce



PDMs offer several advantages over other methods (such as arrow diagrams):

• The technique provides flexibility in sequencing activities by allowing four types of logical dependencies. By comparison, arrow diagrams are limited to finish-to-start dependencies.

• The technique does not require the use of “dummy” activities whenever multiple dependencies are needed in a schedule.

• Finally, the technique adds the concept of lag and lead times between activities.

Figure 6-11, PMBOK® Guide, p. 160 shows a network using PDM.

2. Dependency Determination: The following four categories of dependencies are used during activity sequencing:

• Mandatory dependencies: Also referred to as “hard logic,” mandatory dependencies are inherent in the nature of the work and often involve physical or technical limitations of some kind. For example, you cannot shingle the roof of a building until the roof has been built. Mandatory dependencies may also occur because of legal or contractual requirements.

• Discretionary dependencies: Known as “soft logic” or “preferential logic,” these optional dependencies are usually chosen because they represent “best practices” or there is a preferred approach even though other approaches would also be acceptable.

• External dependencies: These dependencies usually involve interfaces outside the project and are usually outside the direct control of the project team. Examples include waiting on delivery of hardware from an outside source or waiting on delivery of aircraft engines before installation in the airframe.

• Internal dependencies: Whether they are mandatory or discretionary, these dependencies are within the direct control of the project team (direct contrast with external dependencies).

3. Leads and Lags: Adjustment of lead and lag times may help define the timing of the work more accurately. A lead time allows the successor (follow-on) task to be accelerated. Conversely, a lag time delays the successor activity.



Two Key Outputs for Sequence Activities (PMBOK® Guide, p. 159):

1. Project Schedule Network Diagrams: A schematic display of the project activities and their logical relationships, most often using PDM as the method of display. Note: Although coverage of arrow diagrams was removed from the PMBOK® Guide, they are still on the exam for many people.

2. Project Documents Updates: As a result of sequencing, the following documents could be updated:

• Activity lists and attributes

• Milestone list and risk register

See course slides #4-3 through #4-17 for examples of network diagrams and key issues associated with them.

6.4 Estimate Activity Resources (PMBOK® Guide, p. 160)

Determining what resources (people, equipment, material, and facilities) will be needed, along with the associated quantities and time frames. Resource issues also apply to the cost estimating process.

Estimate Activity Resources


1. Schedule management plan 2. Activity list 3. Activity attributes 4. Resource calendars 5. Risk register 6. Activity cost estimates 7. Enterprise environmental factors 8. Organizational process assets

1. Expert judgment 2. Alternative analysis 3. Published estimating data 4. Bottom-up estimating 5. Project management

software

1. Activity resource requirements

2. Resource breakdown structure (RBS)

3. Project documents updates

Eight Key Inputs for Estimate Activity Resources (PMBOK® Guide, p. 162):

1. Schedule Management Plan: Identifies the desired level of accuracy and units of measure for resources (staff hours) and schedule (whether it will be measured in days, weeks, or other units). See Section 6.1.3.1.



2. Activity List: Resource estimates should be done for the associated activities.

3. Activity Attributes: Activity attributes were developed during activity definition and now provide a primary source of data for estimating the resources required for each activity.

4. Resource Calendars: Described in PMBOK® Guide, Sections 9.2.3.2 and 12.2.3.3, the resource calendar system should provide information such as when a resource is available for a work assignment, experience level of a given resource, skill sets possessed by individuals, and geographical location.

5. Risk Register: Potential risk events may affect resource availability.

6. Activity Cost Estimates: The comparative cost of specific resources may affect the decision on which resources may be selected.

7. Enterprise Environmental Factors: Information about the existing resource infrastructure (resource availability and skill sets) would be relevant at this step.

8. Organizational Process Assets: Organizational Process Assets that would affect the estimation of resources required to support project activities include:

• Staffing policies

• Procedures for renting or purchasing supplies and equipment

• Historical information about resource usage on similar projects

Five Key Tools for Estimate Activity Resources (PMBOK® Guide, p. 164):

1. Expert Judgment: Appropriate subject matter experts will help judge the accuracy of resource estimates.

2. Alternative Analysis: This analysis considers the various options for doing the work and assures that appropriate resource estimates are available. For example, a project might pursue either of two technological possibilities; there may be a choice between manual or automated tools/processes; or various levels of resource capabilities may be considered.

3. Published Estimating Data: Some industries and trade groups collect and publish cost, schedule, and resource data for specific types of work.



4. Bottom-Up Estimating: If a schedule activity cannot be estimated with reasonable confidence, the work may be decomposed to a lower level to provide more detail. The bottom-up approach then aggregates these estimates at higher levels.

5. Project Management Software: Most project management software is capable of organizing resource data for individual team members or groups (sometimes called resource pools). The software can usually define:

• Resource availability

• Resource rates

• Resource calendars

• Resource breakdown structures (RBS)

Three Key Outputs for Estimate Activity Resources (PMBOK® Guide, p. 165):

1. Activity Resource Requirements: Identifies the type and quantity of resources needed to support each individual schedule activity. If the work was decomposed below the work package (schedule activity), the resource requirements are added (aggregated) to determine total resource needs for the work package. Estimates should include:

• The basis of the estimate (method used)

• Any assumptions that were made

• Resource availability

• Resource quantity

2. Resource Breakdown Structure: Whereas the WBS focuses primarily on activities, the RBS is a hierarchical structure focusing primarily on resources.The RBS identifies activities to which the resources are assigned as well as the associated time frames. The RBS is also useful in determining whether a resource is available in any given time period.

3. Project Documents Updates: Project documents that might be updated include:

• Activity list • Activity attributes • Resource calendars



6.5 Estimate Activity Durations (PMBOK® Guide, p. 165)

Duration estimating coordinates information about activity scope, resource types and quantities, and resource calendars so that a realistic schedule can be developed.Duration estimating has been defined as assessing the number of work periods needed to complete an activity. Estimates should be:

• Produced by the people most familiar with the work (or at least approved by them). This observation refers to the importance of expert judgment.

• Progressively elaborated, in other words, estimates will usually become more accurate as the quality of the input data improves.

• Adjusted for the effects of “elapsed time” (whether or not weekends are treated as work periods). Note: Project management software makes it much easier to assess the effect of these elapsed times on a project schedule.

Duration estimating should also consider the difference between effort and duration. If four people work 10 hours each on a task, the total effort that must be paid for is 40 person-hours. If those four people are working simultaneously, i.e., in parallel, the duration to complete the work will be 10 hours. In summary, durations are used for scheduling and effort is used to estimate costs.

Estimate Activity Durations


1. Schedule management plan 2. Activity list 3. Activity attributes 4. Activity resource requirements 5. Resource calendars 6. Project scope statement 7. Risk register 8. Resource breakdown structure 9. Enterprise environmental factors 10. Organizational process assets

1. Expert judgment 2. Analogous estimating 3. Parametric estimating 4. Three-point estimating 5. Group decision-making

techniques 6. Reserve analysis

1. Activity duration estimates 2. Project documents updates



Ten Key Inputs for Estimate Activity Durations (PMBOK® Guide, p. 167):

1. Schedule Management Plan: Defines the estimating method, desired level of accuracy, and frequency for updates.

2. Activity List: Described in Section 6.2.3.1, durations must be estimated for each activity.

3. Activity Attributes: Described in Section 6.2.3.2.

4. Activity Resource Requirements: Duration estimates are affected by how many resources are assigned to a task (two people can usually complete a task faster than one person). In turn, actual availability of those resources is also a major factor. If resources prove to be unavailable, some form of outsourcing may be required. As mentioned earlier, durations are also affected by relative levels of experience and capability.

5. Resource Calendars: Resource calendars identify the availability and capability of all required resources (people and equipment).

6. Project Scope Statement: Any constraints or assumptions from the scope statement that may affect activity durations. A constraint could be that a key stakeholder has imposed a strict deadline for completion of initial testing. An assumption might be that hurricane activity will not disrupt product testing in your sea coast facility and, therefore, you will meet the planned deadline.

7. Risk Register: Provides the list of potential risk events, the results of risk analysis, and the appropriate response plans.

8. Resource Breakdown Structure: Identifies resources by category (labor, equipment, materials) and type (skill level, grade level, etc.).

9. Enterprise Environmental Factors: Environmental factors that may affect duration estimates include:

• Duration estimating databases • Productivity metrics • Published commercial information



10. Organizational Process Assets: Organizational Process Assets that may affect duration estimates include:

• Historical information on likely durations • Project calendars • Scheduling methodology • Lessons learned

Six Key Tools for Estimate Activity Durations (PMBOK® Guide, p. 169):

1. Expert Judgment: PMI recommends the use of expert judgment guided by historical information whenever the combination is possible. Expert judgment is crucial because of the potential number of factors that can affect durations.

2. Analogous Estimating: A form of top-down estimating, this approach uses the actual durations of previous, similar activities to estimate the duration of future activities. These estimates are usually adjusted by experts for differences in complexity, size, and risk. Key points:

• The technique is usually applied in the early stages of a project when detailed information is limited and is, therefore, considered a ballpark guesstimate.

• Developing such an estimate is not costly, but the accuracy is limited.

• The technique is most reliable when a) the previous activities are similar in fact and not just in appearance and b) the individuals making the estimates have the needed expertise (for example, expert judgment was the first tool).

3. Parametric Estimating: For some tasks, duration estimates can be derived from the quantity needed multiplied by the appropriate productivity rate. For example, if a drawing takes approximately 10 hours and you need 50 drawings, the estimated duration of creating the drawings would be 500 hours.

4. Three-Point Estimating: Such estimates can improve accuracy by considering risk. This technique calculates an expected average duration from the following three estimates:

• Optimistic: The best-case scenario as seen by someone familiar with the work.

• Pessimistic: The worst-case scenario as seen by someone familiar with the work.



• Most Likely: The most likely scenario as seen by someone familiar with the work.

In similar fashion, a well-known technique for doing the same thing is PERT (Program Evaluation and Review Technique). The differences among PERT, three-point estimate, and CPM (Critical Path Method) will be discussed in the next process on schedule development.

5. Group Decision-Making Techniques: The use of group processes such as brainstorming, Delphi, and nominal group may help teams produce more accurate estimates. PMI also believes that this teaming process will usually lead to increased commitment in achieving the schedule.

6. Reserve Analysis: Contingency reserves (sometimes referred to as time reserve or buffers) are sometimes added to duration estimates to account for risk or uncertainty. Contingency may be a percentage of the overall schedule or a fixed number of time periods. If used, reserve time should be documented along with assumptions and other data. Ultimately, reserve time may be used, reduced, or eliminated (as needed).

PMI has identified the following methods for handling reserve. These methods also apply to cost estimating.

• Contingency Reserves: This amount of time is allocated within the schedule baseline for “known-unknowns”, i.e., the time associated with handling identified risks. These reserves may be associated with specific activities or aggregated into buffers (see PMBOK® Guide, Figure 6-19, p. 178, Critical Chain).

• Management Reserves: An amount of duration withheld from the baseline and intended for “unknown-unknowns”, i.e., unforeseen problems that may affect the schedule.

Two Key Outputs for Estimate Activity Durations (PMBOK® Guide, p. 172):

1. Activity Duration Estimates: Quantitative assessments of the number of work periods (hours, days, and so on) needed to complete an activity (and by extension, to complete the entire project). PMI recommends that these estimates should also include a range of possible results. Note: Duration estimates for different activities are assumed to be statistically independent (the estimate of one task does not determine or influence the duration estimate of a different task).



2. Project Documents Updates: Documents that may be updated include:

• Activity attributes

• Assumptions inherent in the duration estimates

6.6 Develop Schedule (PMBOK® Guide, p. 172)

Schedule development builds upon the previous processes (schedule management plan, activity list, sequencing, resource estimates, and duration estimates) to establish the project schedule. Entering these data into a scheduling tool (usually software such as Microsoft Project or Primavera or others) will establish planned start and finish times for each task. The approved schedule becomes the baseline for tracking progress.

Develop Schedule


1. Schedule management plan 2. Activity list 3. Activity attributes 4. Project schedule network diagrams 5. Activity resource requirements 6. Resource calendars 7. Activity duration estimates 8. Project scope statement 9. Risk register 10. Project staff assignments 11. Resource breakdown structure 12. Enterprise environmental factors 13. Organizational process assets

1. Schedule network analysis 2. Critical path method 3. Critical chain method 4. Resource optimization

techniques 5. Modeling techniques 6. Leads and lags 7. Schedule compression 8. Scheduling tool

1. Schedule baseline 2. Project schedule 3. Schedule data 4. Project calendars 5. Project management plan

updates 6. Project documents

updates

Thirteen Key Inputs for Develop Schedule (PMBOK® Guide, p. 174):

1. Schedule Management Plan: Identifies the scheduling method (such as critical path method or critical chain method) for creating the schedule.

2. Activity List: Described in Section 6.2.3.1 (identifies the activities that must be scheduled).



3. Activity Attributes: Described in Section 6.2.3.2 (provides the details for each activity).

4. Project Schedule Network Diagrams: Described in Section 6.3.3.1 (shows the sequencing).

5. Activity Resource Requirements: Described in Section 6.4.3.1 (types and quantities of resources needed).

6. Resource Calendars: Described in Sections 6.4.1.4 and 6.5.1.5 (availability and capability of resources).

7. Activity Duration Estimates: Described in Section 6.5.3.1 (the number of work periods needed to complete project activities).

8. Project Scope Statement: Any constraints or assumptions that may affect the schedule. PMI has identified two categories of time constraints that may potentially affect the schedule:

• Imposed dates: Mandates from someone else (customer, upper management, or a court-imposed date). Project management software allows date constraints such as “Start No Earlier Than” and “Finish No Later Than.”

• Key events or major milestones: Completion of certain deliverables might be desired, requested, or demanded by specified dates.

9. Risk Register: Described in Section 11.2.3.1 (identifies risk events that may affect the schedule).

10. Project Staff Assignments: Identifies which resources are assigned to specific activities.

11. Resource Breakdown Structure: Provides the details needed to organize and report as to how resources are affecting the schedule.

12. Enterprise Environmental Factors: Environmental factors that may affect schedule development include:

• Standards and communication channels

• Scheduling tool selected for building the schedule



13. Organizational Process Assets: Organizational Process Assets that may affect schedule development include:

• Scheduling methodology

• Project calendar

Eight Key Tools for Develop Schedule (PMBOK® Guide, p. 176):

1. Schedule Network Analysis: Techniques that generate the project schedule using a schedule model and various analytical techniques such as critical path method, critical chain method, what-if analysis (simulation), resource optimization (resource leveling and smoothing), and so on.

2. Critical Path Method: Calculates theoretical start and finish dates for all schedule activities without regard to resource limitations. The technique:

• Uses a forward and backward pass to determine early and late times.

• Calculates available float or slack (float or slack indicates where any flexibility in the schedule exists to delay activities without delaying the project).

• Determines the critical path (the longest path, the path with zero float or the least float available, the shortest possible duration for the project). It is possible to have more than one critical path, which would make the schedule more risky.

• The critical path may have positive total float if the project is ahead of schedule or negative total float if the project is behind schedule.

• A near-critical path exists when the duration of a path is almost as long as that of the critical path. If the activities on such a path are subject to considerable risk or variation, those activities must be monitored as carefully as those on the critical path.

Historically, the exam has asked numerous questions about PERT (Program Evaluation and Review Technique) as well as any differences between PERT and CPM (Critical Path Method). The course slides will examine these issues.

3. Critical Chain Method: This technique modifies the schedule to account for limited resources. The critical path is first determined using a normal process without resource limitations. Next, resource limitations are applied and a resource-constrained schedule is produced. The resource-constrained critical path is known as the critical chain.



Non-work activities called duration buffers are added to the end of activity sequences. One of these buffers is known as the project buffer and is placed at the end of the critical chain. Other buffers, called feeding buffers, are placed at any point where non-critical tasks feed into the critical chain. The size of each buffer should reflect the uncertainty associated with that sequence of tasks. Compared to traditional approaches, the schedule is managed by monitoring the duration buffers (comparing remaining buffer amounts to remaining activity durations) instead of managing float and the critical path.

4. Resource Optimization Techniques: The two following techniques are identified by PMI:

a) Resource Leveling: This technique applies when a schedule has already been produced but one of the following problems exists with resources:

• There are fewer resources available than the schedule requires

• Certain resources are only available at specific times

• Resource usage needs to be kept at a constant level

When any of these resource constraints exist, the goal is to balance demand for resources with the available supply. The most popular response is as follows:

• In time periods with too much work for the available resources, some of the work may be moved into other time periods. This is often done by moving tasks with available positive float. This guideline or rule of thumb is referred to as a “heuristic” by some people.

• Note: Be aware that resource leveling tends to result in a project duration that is longer than originally planned.

b) Resource Smoothing: Conceptually similar to resource leveling, you must operate within predefined resource constraints or limits. The difference is that, with smoothing, activities must be performed within the available float. The schedule is not allowed to slip. Therefore, it may not be possible to optimize all resources.

5. Modeling Techniques: Two highly related techniques are identified:

a) What-If Scenario Analysis: As the name suggests, this analysis uses the power of the computer to consider various potential scenarios. In this way, you can model the potential effects of different internal or external events, such



as: a component is not delivered on time, defective parts arrive, a labor strike occurs, or an extreme weather problem (hurricane, blizzard, lightning strike) occurs. This technique is related to the use of simulation programs.

b) Simulation: Monte Carlo simulation calculates numerous potential project durations under differing assumptions and produces a distribution of possible results with associated probabilities. There are numerous commercially available software programs that will perform such a simulation. This process provides invaluable feedback about the feasibility of the schedule and may also help in devising contingency plans.

6. Leads and Lags: Leads and lags may be adjusted to develop viable, realistic schedules. They make it easier to delay or accelerate work.

7. Schedule Compression: Seeking ways to shorten the schedule without changing the scope. There are two primary techniques:

• Crashing: Exploring cost and schedule trade-offs to shorten the schedule for the least incremental cost. The technique essentially involves adding resources to critical path activities but will almost always increase project cost.

• Fast tracking: Doing more activities in parallel (may also apply to overlapping phases of a project, sometimes called concurrent engineering). Note that fast tracking usually increases risk because it requires increased coordination of resources and may result in rework.

8. Scheduling Tool: Automated scheduling tools make it easier to produce a schedule and to track changes to the schedule.

Refer to Course Slides #4-18 through #4-32 for additional information on Three-Point Estimates, CPM, PERT, crashing, and fast tracking.

Six Key Outputs for Develop Schedule (PMBOK® Guide, p. 181):

1. Schedule Baseline: The approved schedule, which then becomes the plan against which to measure performance. The schedule baseline is a component of the project management plan and is also part of the triple constraint.

2. Project Schedule: This output refers to various possible presentations of the resulting schedule. PMI states that schedules remain preliminary until resource assignments have been confirmed. They also say that the schedule can be



presented in summary form (such as a high-level master schedule) or in detail.Possible formats for presentation include:

Project schedule network diagrams which show activity dependencies (logic) and the critical path.

Bar charts (also called Gantt charts) which are easy to read and used frequently in presentations. Gantt charts show activity start and finish dates, activity durations, and dependencies. They are especially good for showing progress or variance. They may also be used to display summary tasks, which are sometimes referred to as hammock activities (a group of related schedule activities aggregated at a summary level).

Milestone charts: You need to know the definition of a milestone: an important event with zero duration, that is, an important point in time.Milestone charts are a good way to communicate high-level schedule status to customers and upper management.

See Figure 6-21 on PMBOK® Guide, p. 183 for illustrations.

3. Schedule Data: Supporting data for the schedule include:

• Activities, attributes, milestones, assumptions, and constraints

• Resource requirements by time period (displayed in a resource histogram)

• Alternative schedules

• Contingency reserves

4. Project Calendars: Some practitioners refer to this as the working calendar.The default working calendar in the Microsoft Project software is Monday through Friday, 8 am to 5 pm daily. The project calendar distinguishes time periods available to perform work from those that are not available.

5. Project Management Plan Updates: Relevant portions of the project plan that might be updated include the:

• Schedule baseline

• Schedule management plan




• Activity resource requirements (especially if resource leveling has been used)

• Activity attributes (any changes in resources, durations, risks, assumptions, etc.)

• Calendar (standard working days or weeks, etc.)

• Risk register

6.7 Control Schedule (PMBOK® Guide, p. 185)

Controlling the schedule involves monitoring schedule status and managing schedule changes. Schedule change control is concerned with the usual factors:

• Determining the current status of the schedule

• Influencing the factors that create schedule changes

• Determining (and tracking) that schedule changes have occurred

• Managing the changes as they occur

Control Schedule


1. Project management plan 2. Project schedule 3. Work performance data 4. Project calendars 5. Schedule data 6. Organizational process

assets

1. Performance reviews 2. Project management software 3. Resource optimization techniques 4. Modeling techniques 5. Leads and lags 6. Schedule compression 7. Scheduling tool

1. Work performance information 2. Schedule forecasts 3. Change requests 4. Project management plan

updates 5. Project documents updates 6. OPA updates

Six Key Inputs for Control Schedule (PMBOK® Guide, p. 187):

1. Project Management Plan: As described earlier, the project management plan contains the schedule management plan and the schedule baseline. The schedule management plan establishes how the schedule will be managed and how changes will be processed. The baseline is compared to actual outcomes to determine if preventive actions, corrective actions, or changes are needed.



2. Project Schedule: The most recent, approved project schedule is the baseline. It is this baseline that will change if schedule changes are approved.

3. Work Performance Data: Provides information on whether planned dates have been met. Activities are classified as to whether they have started or finished and metrics are tracked (such as actual duration, remaining duration, and percent complete).

4. Project Calendars: Described in Section 6.6.3.4, calendars identify time periods available for completing work and forecasting remaining work.

5. Schedule Data: Described in Section 6.6.3.3, detailed schedule data is updated as necessary during control of the schedule.

6. Organizational Process Assets: Organizational Process Assets that may affect schedule control include:

• Formal and informal policies regarding scheduling control (changes, preventive action, corrective action, and monitoring actual results)

• Schedule control tools

• Monitoring and reporting methods

Seven Key Tools for Control Schedule (PMBOK® Guide, p. 188):

1. Performance Reviews: Performance reviews compare and analyze planned vs. actual performance data such as start and finish dates, percent complete, and remaining duration. The following techniques may be used in conducting this analysis:

• Trend analysis: Examines performance over time to determine whether performance is improving or deteriorating. Graphical analysis may be used to display any trends, e.g., a line graph.

• Critical path method: Identifying variances on the critical path may provide the best insight into schedule status. Evaluating activity variances on any near-critical paths can help identify schedule risks.

• Critical chain method: Compares remaining buffer amounts to buffer amounts needed to protect the schedule (based on schedule risk).

• Earned value management: Provides schedule measures such as schedule variance and schedule performance index. If earned value is used, a method for measuring “in-progress” activities must



be adopted (e.g., percent complete or the 50-50 rule). An important part of schedule control is to determine whether schedule variations are sufficient to require responses such as corrective or preventive actions. The details of earned value will be covered in the cost management chapter. If earned value is not used, a generic schedule variance may be calculated using the formula:

Plan - Actual.

2. Project Management Software: Provides the means to track planned versus actual dates and to forecast expected future performance.

3. Resource Optimization Techniques: Used to optimize the distribution of work against the available resources (Section 6.6.2.4).

4. Modeling Techniques: Uses what-if analysis and simulation to analyze various scenarios and determine the probability of different schedule outcomes (Section 6.6.2.5).

5. Leads and Lags: Used to bring the schedule back in line with the plan by delaying or accelerating work (Section 6.6.2.6).

6. Schedule Compression: Techniques such as crashing and fast tracking to realign the current schedule with the original plan/baseline (Section 6.6.2.7).

7. Scheduling Tool: The schedule data are updated to reflect actual progress.Manual or automated scheduling methods are used to produce an updated schedule.

Six Key Outputs for Control Schedule (PMBOK® Guide, p. 190):

1. Work Performance Information: For schedule purposes, the schedule variance and the schedule performance index should be calculated and reported to appropriate stakeholders.

2. Schedule Forecasts: Forecasts of future outcomes are updated based on work performance information available at the time. Earned value indicators are often used for this purpose, e.g., estimate at completion (EAC) and variance at completion (VAC).

3. Change Requests: If change requests occur during analysis of schedule variances, they should be processed using integrated change control.



4. Project Management Plan Updates: Updates to the project management plan may include:

• Schedule baseline (in response to approved change requests)

• Schedule management plan (changes in the way the schedule is to be managed)

• Cost baseline (additional costs incurred in compressing the schedule)


• Schedule data (New network diagrams may be developed to show remaining duration and/or modifications to the original plan.).

• Project schedule (An updated schedule may be produced that reflects approved changes.).

• Risk register (The risk register and/or risk response plans may be updated based on the use of schedule compression techniques.).

6. Organizational Process Assets Updates: Organizational Process Assets that may be updated as a result of schedule control include:

• The causes of variances that have occurred

• Corrective actions chosen and the rationale

• Other lessons learned with respect to schedule control

Other Topics:

Monte Carlo analysis: You should know that CPM and PERT tend to understate schedule durations in comparison to Monte Carlo. This is because Monte Carlo simulation can account for path convergence whereas CPM and PERT cannot. This topic is addressed in more detail in the chapter on risk management. Seecourse slide #4-33.

GERT (Graphical Evaluation and Review Technique): This technique was removed from the PMBOK® Guide but may remain on the exam. It is a sophisticated schedule development tool that can handle loops (activities that occur more than once) and conditional branches (activities that occur only if something else happens first, i.e., “If–Then” logic).

Note: Additional practice network diagrams are included in course slides #4-34 through #4-53



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Self-Study Drill Practice: Time Management

Question Answer

1. Name four categories of dependencies used in activity sequencing.

Note: All page numbers in this drill practice refer to the study guide unless otherwise indicated.

1. a. Mandatory (also called “hard logic”) b. Discretionary (also called preferred, preferential, or “soft logic”) c. External (work not under the direct control of the project team) d. Internal (work under the direct control of the project team) (p. 4-8)

2. Name two methods of compressing project duration.

2. Crashing and Fast Tracking (p. 4-20).

3. Describe crashing: 3. Adding resources to critical path activities to reduce the overall project schedule.

Usually increases cost (p. 4-20).

4. Describe fast tracking: 4. Doing activities in parallel that were initially planned in sequence (p. 4-20).

Usually increases risk because of additional coordination of resources and the possibility of rework.

5. What is total float (slack)? 5. The amount of time an activity can be delayed without delaying the project finish date. Some practitioners also refer to total float as either path float or shared float. (Course slides 4-9, 4-17)

6. What is free float (slack)? 6. The amount of time an activity can be delayed without delaying the early start of any immediate successor activities. Float owned independently by an activity. (Course slides 4-10, 4-17)



7. What is resource leveling? 7. Any form of network analysis in which scheduling decisions are driven by resource management concerns (p. 4-19).

In practice, this usually means rescheduling tasks into time periods where sufficient resources are available.

The usual result of this practice is to push out the project end date. Therefore, in an ideal world, resource leveling should be limited to activities with positive float, ifpossible.

8. How is schedule variance calculated? 8. Plan - Actual (pp. 1-7 and 4-23/24)

If a task is supposed to take five days and actually takes ten days, the variance is negative five days.

Negative variances mean the task took longer than expected.

9. What are the three tools of sequence activities?

9.Precedence diagramming method Dependency determination Leads and lags (pp. 4-7/8)

10. What are heuristics? 10. Problem-solving techniques producing “acceptable” or “good enough” results; often called rules of thumb. (p. 4-19)

11. What is a milestone? 11. An activity with zero duration and requiring no resources; normally used to mark the beginning or ending of a task or deliverable. (p. 4-5)



12. What is the critical path? 12. The longest path through the project network. Also the path with the least slack (float).

Activities on the critical path usually have zero float (but not always as the statement above implies) (p. 4-18 and course slides 4-9, 4-17).

13. Name three major advantages of precedence diagrams.

13. a. They do not require dummy activities. b. They increase scheduling flexibility by allowing the overlapping of activities. c. They deal with lag more easily. (p. 4-8)

14. Name and define each of the four types of dependencies or logical relationships used in activity sequencing.

14. a. Finish-to-start: initiation of the successor depends on completion of the predecessor. b. Finish-to-finish: completion of the successor depends on completion of the predecessor. c. Start-to-start: initiation of the successor depends on initiation of the predecessor. d. Start-to-finish: completion of the successor depends on initiation of the predecessor (p. 4-7)

15. What are the advantages of a bar (Gantt) chart?

15. Easy to construct and easy to read; bar charts are an easy way to show progress or status (i.e., schedule variances) (p. 4-21).

16. Define activity duration estimating. 16. Assessing the number of work periods it will take to complete an activity (p. 4-15).

17. What are the two outputs of estimate activity durations?

17. Activity duration estimates and project documents updates (pp. 4-15 & 4-16).



18. What is a hammock activity? 18. A summary level task that shows the start of the first activity and the end of the last activity in a series of related activities.May be displayed as part of a Gantt chart (p. 4-21).

19. What are the inputs to define activities?

19. The schedule management plan, scope baseline, enterprise environmental factors, and organizational process assets (p. 4-4).

20. What is the schedule baseline? 20. It is the approved project schedule; i.e., the original plan plus or minus approved changes.

The baseline is used to measure and report schedule performance. It should not be changed without proper review and approval (p. 4-20).

21. What information does a simulation provide?

21. A range of potential project durations with associated probabilities (p. 4-20).

22. What is an indicator of flexibility in the schedule?

22. Activities that have positive slack (float) provide flexibility as to start times and resource usage (p. 4-18, tool #2, bullet #2).

23. What is a dummy activity? 23. A task with zero duration; used in arrow diagram networks to correctly show multiple dependencies (logical relationships). Not needed in precedence diagrams (p. 4-8, tool #1 and course slide 4-3).

24. Who should develop the project schedule?

24. The project team (it is the PM’s responsibility, but like development of most plans, the expertise of various team members is needed to complete the schedule) (Same logic as for project management plan, p. 2-19).



25. What are the seven major scheduling processes?

25.Plan schedule management Define activities Sequence activities Estimate activity resources Estimate activity durations Develop schedule Control schedule (p. 4-1)

26. What is a conditional diagram and what does it allow?

26. GERT (Graphical Evaluation and Review Technique) is an example of a diagramming technique that allows for loops (repetitive tasks) and conditional branches (e.g., design update only needed if inspection detects errors). (p. 4-25)

27. What are the differences between CPM and PERT?

27.CPM = Critical Path Method • Uses a single duration estimate • Focus is on calculating float to

determine scheduling flexibility PERT = Program Evaluation and Review Technique • Uses three time estimates to calculate

a weighted average duration estimate • Allows calculation of variance so that it

is possible to assess schedule risk • Uses a calculated expected value vs. a

single most likely estimate (Course slides 4-18 to 4-20)

28. For schedule control purposes, what capabilities does project management software provide?

28. a. Tracking of planned versus actual dates (i.e., variances) b. Forecasting the potential effects of schedule changes (p. 4-24, tool #2)

29. The arrow diagram method is limited to what single kind of logical dependency?

29. Finish-to-start (p. 4-8 and course slide 4-43)



30. List two ways to graphically portray a project network.

30.• Activity-on-Arrow (Arrow Diagram) • Activity-on-Node (Precedence

Diagram)(pp. 4-7/8 and course slides 4-3 to 4-5)

31. What is the relationship between the activity list and the WBS?

31. The activity list includes all activities needed to complete the project. It includes the schedule activities below the work packages (pp. 4-4/5).

32. What is the formula to calculate a PERT-weighted average estimate?

32.[o + 4m + p] / 6

o = optimistic time m = most likely time p = pessimistic time

(p. 1-7 and course slides 4-22 to 4-27)

33. What is the formula for a PERT standard deviation?

33. (p – o) / 6 (p. 1-7 and course slides 4-22 to 4-27)

34. What is slack or float? 34. The amount of time a task can be delayed without delaying the project (Course slides 4-9 and 4-17).

35. What is lag? 35. The amount of waiting time between tasks. Therefore, lag is not the same as float (p. 4-8, tool #3)!

36. What is the schedule management plan?

36. A component of the project management plan that specifies how the schedule will be developed, managed, executed, and controlled. (pp. 4-1 and 4-3)