1. Key Definitions
Activity: An element of work performed during the course of a project. (Normally has duration, cost, and resource requirements.)
Baseline: The original plan plus or minus approved changes.
Arrow Diagram Method (ADM): A network diagramming technique in which activities are represented by arrows. The tail of the arrow represents the start and the head of the arrow represents the end of the activity. Activities are connected at points called nodes to illustrate the sequence in which activities are expected to be performed. Also called Activity-On-Arrow (AOA).
Backward Pass: The calculation of late finish and start dates for the uncompleted portions of all network activities. Determined by working backwards through the network logic from the project’s end date.
Concurrent Engineering: Generally speaking, an approach to project staffing that calls for the implementers to be involved in the design phase. (sometimes confused with fast tracking.)
Crashing: Taking action to decrease the total project duration after analyzing a number of alternatives to determine how to get the maximum duration compression for the least cost.
Critical Activity: An activity on a critical path.
Critical Path: The series of activities which determines the earliest completion of the project. The critical path is usually defined as those activities with float less than or equal to a specified value (usually zero).
Critical Path Method (CPM): A network analysis technique used to predict project duration by
analyzing which path has the least amount of scheduling flexibility. Early dates are calculated using a forward pass; late dates are calculated using a backwards pass.
Data Date (DD): The point in time that separates actual (historical) data from future (scheduled) data. Also called as-of date.
Dummy Activity: An activity of zero duration used to show a logical relationship in the arrow diagramming method. Dummy activities are used when logical
relationships cannot be completely or correctly described with regular activity arrows. Dummies are shown graphically as a dashed line headed by an arrow.
Duration (DU): The number of work periods (not including holidays and other non- working periods) required to complete an activity or other project element.
Early Finish Date (EF): In the critical path method, the earliest possible date in which the
uncompleted portions of an activity or project can complete. Can change as the project progresses.
Early Start Date (ES): In the critical path method, the earliest possible date in which the uncompleted portions of an activity or project can start Can change as the project progresses.
Effort: The number of labor units required to complete an activity or other project element. Should not be confused with duration.
Event-on-Node: A network diagramming technique in which events are represented by boxes (or nodes) connected by arrows to show the sequence in which the events are to occur.
Fast Tracking: Compressing the project schedule by overlapping activities that would normally be done in sequence (such as design and construction).
Float: The amount of time that an activity may be delayed from its early start without delaying the project finish date. (Also called slack, total float, and path float).
Forward Pass: The calculation of the early start and early finish dates for the uncompleted portions of all network activities.
Free Float (FF): The amount of time an activity can be delayed without delaying the early start of any immediately succeeding activities.
Gantt Chart: A graphic display of schedule-related information using bars.
Hammock: An aggregate or summary activity.
Hanger: An unintended break in a network path. Hangers are usually caused by missing activities or missing logical relationships.
Lag: A modification of a logical relationship which directs a delay in the successor task.
Late Finish Date (LF): In the critical path method, the latest possible date that an activity may be completed without delaying a specified milestone (usually the project finish date).
Late Start Date (SF): In the critical path method, the latest possible date that an activity may begin without delaying a specified milestone (usually the project finish date).
Lead: A modification of a logical relationship which allows an acceleration of the successor task. For example, in a FS relationship with a 10 day lead, the successor can start 10 days prior to the completion of the predecessor.
Level of Effort (LOE): Support type activity (e.g., vendor or customer liason) that does not readily lend itself to measurement of discrete accomplishment. Generally characterized by a uniform rate of activity over a specific period of time.
Logical Relationship: A dependency between two project activities or between an activity and a milestone. Four possible types: FS, FF, SS, and SF. (see logical relationships under concepts).
Master Schedule: A summary level schedule which identifies the major activities and milestones.
Milestone: A significant event in the project, usually completion of a major deliverable.
Milestone Schedule: A summary level schedule which identifies the major milestones.
Path Convergence: In mathematical analysis, the tendency of parallel paths of approximately equal duration to delay the completion of the milestone where they meet.
Precedence Diagram Method (PDM): A network diagramming technique in which activities are represented by nodes. Activities are linked by precedence relationships to show the sequence in which the activities are to be performed.
Program Evaluation and Review Technique (PERT): An event-oriented network analysis technique used to estimate project duration when there is a high degree of uncertainty with the individual activity duration estimates.
Project Network Diagram: Any schematic display of the logical relationships of project activities. Always drawn from left to right to reflect project chronology. Often incorrectly referred to as a “PERT chart”.
Remaining Duration (RDU): The time needed to complete an activity.
Resource Leveling: Any form of network analysis in which start and finish dates are driven by resource management concerns.
Resource-Limited Schedule: A project schedule whose start and finish dates reflect expected resource availability. The final project schedule should always be resource limited.
Scheduled Finish Date (SF): The point in time work was scheduled to finish on an activity. The scheduled finish date is normally within the range of dates delimited by the early finish date and the late finish date.
Scheduled Start Date (SS): The point in time work was scheduled to start on an activity. The scheduled start date is normally within the range of dates delimited by the early start and late start dates.
Slack: Synonymous with float.
Time-Scaled Network Diagram: Any project network diagram drawn is such a way that the positioning
and length of the activity represents its duration. Essentially, it is a bar chart that includes network logic.
Total Float: Synonymous with float.
Work Item: Synonymous with activity.
Time Management
Activity Definition:
2. The process of identifying and documenting the specific activities that must be performed to produce the various project deliverables identified in the WBS.
3. Define the activities such that the project objectives will be met.l,
4. Inputs include: WBS, scope statement, historical information, constraints, and assumptions
5. Methods used during activity definition:
6. Decomposition: Involves subdividing project elements into smaller, more manageable components. Differs from scope definition in that the outputs are activities (action steps) rather than deliverables
7. Templates: Activity lists or portions of activity lists from previous projects.
8. Outputs include: Activity list, supporting detail including assumptions and constraints, and WBS updates
Activity Sequencing:
9. The process of identifying and documenting interactivity dependencies.
10. Activities must be sequenced accurately.
11. Inputs include: Activity list, product description, mandatory dependencies, discretionary dependencies, external dependencies, constraints, and assumptions.
12. Methods used during activity sequencing are: Precedence Diagramming Method, Arrow
Diagramming Method, conditional diagramming methods, and network templates.
13. Network templates can include an entire project or only a portion of it. (portions are referred to as subnets or fragnets.) Subnets are useful where a project inincludes several identical or nearly identical features such as floors on a high-rise office building or program modules on a software project.
14. Outputs include: Project network diagram and activity list updates.
Activity Duration Estimating:
15. The process of estimating the number of work periods needed to complete each identified activity.
16. Inputs include: Activity list, constraints, assumptions, resource requirements, resource capabilities, and historical information. .
17. Methods used during activity duration estimating include: expert judgment, analogous estimating (top-down estimating), and simulation.
18. Outputs include: Activity duration estimates, basis of estimates, and activity list updates.
Schedule Development:
19. The process of analyzing activity sequences, durations, and resource requirements to create the project schedule.
20. Inputs include: Activity list, constraints, assumptions, resource requirements, resource capabilities, and historical information.
21. The methods used in schedule development include: expert judgment, analogous estimating, and simulation.
22. Outputs from schedule development: activity duration estimates, basis of estimates, and activity list updates.
Schedule Control:
23. The process of controlling changes to the project schedule.
24. Inputs include: Project schedule, performance reports, change requests, and schedule management plan.
25. Methods for schedule control include: Schedule change control system, performance measurement, additional planning, and project management software.
26. Outputs include: schedule updates, corrective action, and lessons learned.
Time Management
Concepts
Scheduling Charts:
27. Gant:
28. Bar oriented
29. In pure form, a gant does not show task dependencies and relationships.
30. Milestone:
31. Consumes no resources or duration.
32. Marks the start or finish of a significant event.
33. Network:
34. Shows task relationships and dependencies.
35. Sometimes incorrectly referred to as a PERT chart.
Hard Coded Constraints:
36. Must Start/Finish On
37. Start No Earlier/Later Than
38. Finish No Earlier/Later Than
39. As soon as possible (ASAP) (Calculated using forward pass)
40. As late as possible (ALAP) (Calculated using backwards pass)
Time Mgmt Concepts
Diagram Techniques:
Precedence diagram Method (PDM):
41. Also called Activity on Node.
42. Four types of logical relationships:
43. Finish to Start: The predecessor activity must finish before the successor activity can start.
44. Finish to Finish: The predecessor activity must finish before the successor activity can finish.
45. Start to Start: The predecessor activity must start before the successor activity can start.
46. Start to Finish: The predecessor activity must start before the successor activity can finish.
47. Also can show lead or lag time.
48. Lead is the same as negative lag.
Arrow Diagram Method (ADM):
49. Also called Activity on Arrow
50. Arrows represent activities while nodes represent the dependencies
51. May require the use of dummy activities to define all logical relationships correctly
52. Only shows “Finish to start” relationships
Conditional Diagramming Methods:
53. GERT and System Dynamics models
54. Allows for nonsequential activities such as loops or conditional branches
TIME
Project Time Management
The processes required to ensure timely completion of the project.
Activity
Normally has an expected duration, an expected cost, and expected resource requirements.
Identifying and documenting the specific activities performed to produce deliverables.
Critical Path
In a project network diagram, the series of activities which determines the earliest completion of the project. The critical path will generally change from time to time as activities are completed ahead or behind schedule. Although normally calculated for the entire project, the critical path can also be determined for a milestone or subproject. The critical path is usually defined as those activities with float less than or equal to a specified value, often zero.
Float
The amount of time that an activity may be delayed from its early start without delaying the project finish date.
Project Time Management (6)
1. Activity Definition (Planning)
Involves identifying and documenting the specific activities that must be performed in order to produce the deliverables and sub-deliverables identified in the WBS.
2. Activity Sequencing (Planning)
Involves identifying and documenting interactivity dependencies, which must be sequenced accurately in order to support later development of a realistic and achievable schedule.
3. Activity Duration Estimating (Planning)
Involves assessing the number of work periods likely to be needed to complete each identified activity.
4. Schedule Development (Scheduling)
Process of formalizing acceptance of the project scope by the stakeholders. It requires reviewing work products and results to ensure that all were completed correctly and satisfactorily.
5. Schedule Control (Scheduling)
Is concerned with a) influencing the factors which create scope changes to ensure that changes are beneficial, b) determining that a scope change has occurred, and c) managing the actual changes when and if they occur.
Activity Definition (6.1)
1. Inputs
a. Work breakdown structure
b. Scope statement
The project justification and the project objectives contained in the scope statement must be considered explicitly during activity definition.
c. Historical information
d. Constraints
e. Assumptions
2. Tools and Techniques
a. Decomposition
Involves subdividing project elements into smaller, more manageable components in order to provide better management control. Final outputs are described as activities, which are made up of tasks, rather than deliverables (tangible items).
b. Templates
An activity list or a portion thereof, from a previous projects which is usable for a new project.
3. Outputs
a. Activity list
Must include all activities, which will be performed on the project. It should not include any activities which are not required as part of the project scope.
b. Supporting detail
Should be documented and organized as needed to facilitate its use by other project management processes.
c. WBS updates
Project team may identify missing deliverables or may determine that a deliverable description needs to be clarified or corrected. These updates are called refinements.
Activity Sequencing (6.2)
1. Inputs
a. Activity List
b. Product description
Product characteristics often affect activity sequencing.
c. Mandatory dependencies
Those dependencies which are inherent in the nature of the work being done. They often involve physical limitations. Also called hard logic.
d. Discretionary dependencies
Those dependencies that are defined by the project management team. Also called soft logic.
e. External dependencies
Those dependencies that are involve a relationship between project activities and non- project activities.
f. Constraints g. Assumptions
2. Tools and Techniques
a. Precedence diagramming method (PDM)
Method of constructing a project network diagram using nodes to represent the activities and connecting them with arrow that show the dependencies. Also called activity-on-node (AON). Four types of dependencies:
1) Finish-to-start – “From” activity must finish before the “to” activity can start. (Most common)
2) Finish-to-finish – “From” activity must finish before the “to” activity can finish.
3) Start-to-start – “From” activity must start before the “to” activity can start.
4) Start-to-finish – “From” activity must start before the “to” activity can finish. (Rarely used)
b. Arrow diagramming method (ADM)
Method of constructing a project network diagram using arrows to represent the activities and connecting them at nodes to show the dependencies. (AOA). Uses only finish-to-start activities and may require the use of dummy activities.
c. Conditional diagramming methods
Allows for non-sequential activities such as loops or conditional branches; neither are used by first two methods.
d. Network templates
Standardized networks can be used to expedite the preparation of project network diagrams. Subnets are especially useful where project includes several identical or nearly identical features.
3. Outputs
a. Project network diagram
A schematic display of the project’s activities and the logical relationships
(dependencies) among them. Often incorrectly called a PERT chart.
b. Activity list updates
Preparation of the project network diagram may reveal instances where an activity must be redefined in order to diagram the correct logical relationships.
Activity Duration Estimating (6.3)
1. Inputs
a. Activity list b. Constraints c. Assumptions
d. Resource requirements
The duration of most activities will be significantly influenced by the resources assigned to them.
e. Resource capabilities
The duration of most activities will be significantly influenced by the capabilities of the humans and material resources assigned to them.
f. Historical information
Following sources may be available for review:
1) Project files
2) Commercial duration estimating databases
3) Project team knowledge
2. Tools and Techniques
a. Expert judgment
Expert judgment guided by historical information should be used whenever possible.
b. Analogous estimating
Also called top-down estimating, which uses the actual duration of a previous, similar activity as the basis for estimating the duration of a future activity.
c. Simulation
Involves calculating multiple durations with different sets of assumptions. The most common is the Monte Carlo analysis.
3. Outputs
a. Activity duration estimates
Activity duration estimates are quantitative assessments of the likely number of work periods that will be required to complete an activity.
b. Basis of estimates
Assumptions made in developing the estimates must be documented.
c. Activity list updates
Schedule Development (6.4)
1. Inputs
a. Project network diagram
b. Activity duration estimates
c. Resource requirements
d. Resource pool description
Knowledge of what resources will be available at what times and in what patterns is necessary for schedule development.
e. Calendars
Project and resource calendars identify periods when work is allowed. Project calendars affect all resources while resource calendars affect a specific resource or category of resource.
f. Constraints
1) Imposed dates – Completion of certain deliverables by a specified date may be required by the project sponsor, customer or external factors.
2) Key events (Major deliverables) – Completion of certain deliverables by a specified date may be requested by the project sponsor, customer or other stakeholders.
g. Assumptions
h. Leads and lags
2. Tools and Techniques
a. Mathematical analysis
Involves calculating theoretical early and late start and finish dates for all project activities for any resource pool limitations. The most common analysis techniques are:
1) Critical Path Method (CPM) – The focus of CPM is on calculating float in order to determine which activities have the least scheduling flexibility. Calculates a single, deterministic early and late start and finish date for each activity based on specified, sequential network logic and a single duration estimate. The focus of CPM is on calculating float in order to determine which actives have the least scheduling flexibility.
2) Graphical Evaluation and Review Technique (GERT) – Allows for probabilistic treatment of both network logic and activity duration estimates.
3) Program Evaluation and Review Technique (PERT) – Uses sequential network logic and a weighed average duration estimate to calculate project duration. Seldom used today.
b. Duration compression
Duration compression looks for ways to shorten the project schedule without changing the project scope. (See drawing on page 68)
1) Crashing – Cost and schedule trade-offs are analyzed to determine how to obtain the greatest amount of compression for the least incremental cost.
2) Fast Tracking – Doing activities in a parallel that would normally be done in sequence. Fast tracking often results in rework and usually increases risk.
c. Simulation
d. Resource leveling heuristics
Mathematical analysis often produces a preliminary schedule that requires more resources during certain time periods than are available, or requires changes in resource levels that are not manageable. Resource leveling often results in a project duration that is longer than the preliminary schedule. Resource constrained scheduling is a special case of resource leveling where the heuristic involved is a limitation on the quantity of resources available.
e. Project management software
Is widely used to assist with schedule development.
3. Outputs
a. Project schedule
Includes at least planned start and expected finish dates for each detail activity. This remains as a preliminary schedule until resource assignments have been confirmed. Schedule may be presented graphically in one of the following formats:
1) Project network diagram – Date information has been added
2) Bar charts (Gantt) – Show activity and end dates as well as expected durations, but do not usually show dependencies.
3) Milestone charts – Similar to the bar chart but identifies the schedule start or completion of major deliverables and key external interfaces.
4) Time-scaled network diagrams – Are a blend of project network diagrams and bar charts in that they show project logic, activity durations and schedule information.
b. Supporting details
Includes at least documentation of all identified assumptions and constraints.
c. Schedule management plan
Defines how changes to the schedule will be managed.
d. Resource requirement updates
Resource leveling and activity list update may have a significant effect on preliminary estimates of resource requirements.
Schedule Control (6.5)
1. Inputs
a. Project schedule
The approved project schedule, called the schedule baseline, is a component of the overall project plan.
b. Performance reports
Provide information on schedule performance such as when planned dates have been met and which have not. Performance reports may also alert the project team to issues, which may cause problems in the future.
c. Change requests
Change requests may occur in many forms – oral or written, direct or indirect, externally or internally initiated, and legally mandated or optional. Changes may require extending the schedule or may allow accelerating it.
d. Scope management plan
2. Tools and Techniques
a. Schedule change control system
Defines the procedures by which the project schedule may be changed. It includes the paperwork, tracking systems and approval levels necessary for authorizing changes.
b. Performance measurement
Techniques to help access the magnitude of any variations that occur in the performance project. An important part of schedule control is to decide if the schedule variation requires corrective action.
c. Additional planning
Prospective changes may require new or revised activity duration estimates, modified activity sequences, or analysis of alternative schedules.
d. Project management software
3. Outputs
a. Schedule updates
A schedule update is any modification to the schedule information, which is used to manage the project. Revisions are a special category of schedule updates. Revisions are changes to the scheduled start and finish dates in the approved project schedule. Also used to measure performance.
b. Corrective action
Activity performed to bring expected future schedule performance into line with the project plan.
c. Lessons learned
Causes of variances, reasoning behind corrective actions and other type of lessons learned from schedule change.
