Project Time Management
Understand the importance of project schedules and good project time management. Define activities as the basis for developing project schedules. Describe how project managers use network diagrams and dependencies to assist in activity sequencing. Understand the process of sequencing activities and the four types of activity dependencies Use Gantt chart for planning schedule information. Describe how software can assist in project time management.
Project time management involves the processes required to ensure timely completion of a project. Project time management describes the processes and methods required to create and manage appropriate schedules to complete the project.
1. Defining Activities identifies the lowest level of work on the WBS, work packages, that needs to be performed to create the finished product deliverable. 2. Sequencing Activities identifying and documenting the relationships between project activities. 3. Estimating activity resources: estimating how many resources (people, equipment, materials) a project team should use to perform project activities.
4. Estimating activity durations: estimating the number of work periods that are needed to complete individual activities. 5. Developing the schedule: analyzing activity sequences, activity resource estimates, and activity duration estimates to create the project schedule. 6. Controlling the schedule: involves controlling and managing changes to the project schedule.
An activity or task is an element of work normally found on the work breakdown structure (WBS) that has an expected duration, cost, and resource requirements. Activity definition involves developing a more detailed WBS and supporting explanations to understand all the work to be done so you can develop realistic cost and duration estimates. The goal of the defining activities is to ensure that the project team has complete understanding of all the work they must do as part of the project.
Depending on the technique used to create the WBS (refer to chapter 5), typically the work packages are built by decomposing parent activities down into smaller and smaller units of work. The 100% rule is in affect; all of the work packages defined must add up to 100% of the total scope of the project. Not all of the work packages will be defined at the same level of detail.
The main outputs of this process are: Activity list: is a tabulation of activities to be included on a project schedule. The list should include the activity name, an activity number, and a brief description of the activity. Activity attributes: provide more schedule-related information about each activity. Milestone list: is a significant event that normally has no duration.
Sequencing activities means determining the dependencies, or relationships between project activities or tasks. There are three basic reasons for creating dependencies: Mandatory dependencies: inherent in the nature of the work being performed on a project. Ex. write software and then test. Discretionary dependencies: defined by the project team offer the most flexibility; External dependencies: involves the relationships between project and non-project activities. You must determine correct dependencies to create a realistic schedule.
Network diagram is a tool that can be used to showing activity sequencing; Network diagrams: is a schematic display of the logical relationships among, or sequencing of, project activities. Network diagram represents activities that must be done to complete the project. Network diagram has two main formats: 1. Arrow Diagramming Method (ADM) 2. Precedence Diagramming Method (PDM)
1. Arrow Diagramming Method (ADM) Also called activity-on-arrow (AOA) network diagrams. Consists of : Lines with arrows that represent activities. Nodes or circles which represent the starting and ending points of activities. Key Drawback: Can only show finish-to-start dependencies
Lines with arrows represent tasks. Circles with words or numbers represent the begin or end of a task.
1. You draw the first Begin circle or node and then proceed with the tasks that do not have a predecessor, usually the first tasks to be done on the project. These are shown in the diagram as lines A, K, and F. 2. Then you move to the next tasks listed in the WBS in order of precedence. Activity B has a predecessor of A and Activity C has a predecessor of B and so on. Tasks M, G, and L have no successors so we draw their arrows to the End node. 3. You add circles at the end of each arrow as an end point. At the end of the process you then number each circle. 4. Be prepared as you draw this diagram to draw and then erase and redraw as you work your way down the task list.
2. Precedence Diagramming Method (PDM) Consists of: Boxes that represent activities. Arrows that show relationships between activities. More popular than ADM method and used by project management software Better at showing different types of dependencies.
Activity Dependency Types: Finish-to-start [FS] Finish coding module before unit testing. Start-to-start[SS] On several IT projects, a group of activities all start simultaneously, such as the many tasks that occur when a new system goes live. Finish-to-Finish[FF] Quality control efforts cannot finish before production finishes. Start-to-Finish[SF] Phase out legacy system can t finish until x days after new system starts acceptance testing.
Samples of Activity Dependency Types in Microsoft Project:
The task names are for this example shortened to just letters. The lines with arrows are not labeled. Notice that some of the activities (C, F, G, and H) have more than one predecessor; some only have a successor (Begin) and some only have a predecessor (End).
Before estimating activity durations, you must have a good idea of the quantity and type of resources that will be assigned to each activity. Resources are people, equipment, and materials Consider important issues in estimating resources: How difficult/complex will it be to complete specific activities on this project? What is the organization s history in doing similar activities? Are the required resources available? Internal or External? Very important to match the right person with the right task!
The main outputs of the resource estimating process: List of activity resource requirements. Project document updates. A resource breakdown structure.
A resource breakdown structure: is a hierarchical structure that identifies the project s resources by category and type. Resource categories may include: analysts programmers testers Programmers type may include: COBOL programmers Java programmers
After defining activities, determining their sequence, assigning appropriate resources, the next step in time management is duration estimating. Duration includes the actual amount of time worked on an activity plus elapsed time. Effort is the number of workdays or work hours required to complete a task.
People doing the work should help create estimates, and an expert should review them. Duration estimate may be given as: Discrete numbers (2 weeks). Ranges (3 to 5 weeks). Three-point estimate.
Three-point estimate is an estimate that includes an optimistic, most likely, and pessimistic estimate, such as: three weeks for the optimistic, four weeks for the most likely, and five weeks for the pessimistic estimate.
Uses results of the other time management processes (activity definition, sequencing, estimating) to determine the start and end date of the project. Also determines the planned start and completion dates for each activity listed on the WBS. The deliverable from this process is the project schedule.
Tools used for schedule development: Gantt chart. Critical path method. PERT. Critical Chain scheduling.
1. Gantt charts provide a standard format for displaying project schedule information by listing project activities and their corresponding start and finish dates in a calendar format. Symbols include: Black diamonds: milestones. Thick black bars: summary tasks. Lighter horizontal bars: durations of tasks. Arrows: dependencies between tasks.
2. Critical Path Method CPM is a network diagramming technique used to predict total project duration. CPM uses the sequence and duration of activities to determine the total project duration. A critical path for a project is the series of activities that determines the earliest time by which the project can be completed.
The critical path is the longest path through the network diagram and has the least amount of slack or float. Slack or float is the amount of time an activity may be delayed without delaying a succeeding activity or the project finish date.
Produces two key pieces of information: 1. The amount of slack, float for each activity in the schedule. 2. The longest path through the schedule or said in another way the shortest time the project can be completed referred to as the critical path. All activities that fall on this path are referred to as critical path activities.
Calculating the Critical Path: 1. Calculate slack for each activity on the WBS using a network diagram. 2. Find the longest path through the network diagram.
Begin 1 3 6 2 4 5 7 A D E G K F I J C B L End H 2 5 4 5 2 1 7 3 8 3 9 4 (0,2) (2,7) (2,7) (0,2) (5,6) (7,9) (7,9) (9,18) (2,6) (0,4) (3,8) (0,5) (5,12) (8,15) (15,18) (12,15) (4,7) (6,9) (9,18) (10,18) (18,22) (18,22) (4,12) (2,3)
Find the Longest Path: Path 1 = A, D, G, K, L = 22 days Path 2 = A, E, H, K, L = 19 Path 3 = A, E, I, L = 15 Path 4 = B, H, K, L = 20 Path 5 = B, I, L = 16 Path 6 = C, F, J, L = 19 Path 1 [ A,D,G,K,L ] is the critical path duration, because it is the longest path.
Techniques for Shortening a Project Schedule (Schedule Analysis) knowing the critical path helps project manager to make schedule trade-offs: Shortening durations of critical tasks by adding more resources or changing their scope. Project time shortening techniques: Crashing tasks by obtaining the greatest amount of schedule compression for the least incremental cost. Fast tracking tasks by doing them in parallel or overlapping them.
3. Critical Chain Scheduling is a method of scheduling that considers limited resources when creating a project schedule and includes buffers to protect the project completion date unlike CPM which is only based on time.
Availability of scarce (rare) resources: Two tasks are planned to occur simultaneously. A single piece of equipment is available. Equipment is needed full time to complete each task. Critical chain scheduling suggests: Delay one task until the equipment is available (sequential). Find another piece of equipment in order to meet the schedule (parallel).
Multitasking occurs when a resource works on more than one task at a time. Critical chain scheduling attempts to minimize multitasking. Multitasking disadvantages: can delay task completions. often involves wasted setup time, which increases total duration.
Three tasks without multitasking: Three tasks with multitasking:
In traditional estimates, people often add a buffer ( additional time to complete a task) and use it if it s needed or not. Critical chain schedule removes buffers from individual tasks and instead creates: 1. A project buffer, which is additional time added before the project s due date. 2. Feeding buffers, which is additional time added before tasks on the critical path.
4. Program Evaluation and Review Technique (PERT) is a network analysis technique used to estimate project duration when there is a high degree of uncertainty about the individual activity duration estimates. PERT uses probabilistic time estimates-duration estimates based on using optimistic, most likely, and pessimistic estimates of activity durations, or a three-point estimate.
PERT weighted average = optimistic time + 4* most likely time + pessimistic time 6 Example: optimistic time = 8 days, most likely time = 10 days, and pessimistic time = 24 days PERT weighted average = 8 workdays + 4 * 10 workdays + 24 workdays = 12 days 6 Therefore, you d use 12 days on the network diagram instead of 10 when using PERT for the above example.
The main advantage of PERT is that it attempt to address the risk associated with duration estimates. The PERT weighted averages for each activity are added to the network diagram to show the start dates and finish dates for each and the final project end date.
The goal of schedule control is to know the status of the schedule, influence the factors that cause schedule changes, determine that the schedule has changed, and manage changes when occur.
Word-processing software. Spreadsheets help to perform financial calculations. Communication software. Project management software. Decision support models.
Project time management includes the processes required to ensure timely completion of a project. Main processes include: Defining activities. Sequencing activities. Estimating activity resources. Estimating activity durations. Developing the schedule. Controlling the schedule.