6 PROJECT TIME MANAGEMENT

Transcription

1 CHAPTER 6 PROJECT TIME MANAGEMENT LEARNING OBJECTIVES After reading this chapter, you will be able to: 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 relationship between estimating resources and project schedules Explain how various tools and techniques help project managers perform activity duration estimating Use a Gantt chart for planning and tracking schedule information, find the critical path for a project, and describe how critical chain scheduling and the Program Evaluation and Review Technique (PERT) affect schedule development

2 INTRODUCTION Many information technology projects are failures in terms of meeting scope, time, and cost projections. Managers often cite delivering projects on time as one of their biggest challenges and the main cause of conflict. PROJECT TIME MANAGEMENT PROCESSES Project time management, simply defined, involves the processes required to ensure timely completion of a project. Achieving timely completion of a project, however, is by no means simple. There are six main processes involved in project time management: 1. Activity definition Defining activities involves identifying the specific activities that the project team members and stakeholders must perform to produce the project deliverables. 2. Activity sequencing Sequencing activities involves identifying and documenting the relationships between project activities. The main outputs of this process include project schedule network diagrams and project document updates. 3. Activity resource estimating Estimating activity resources involves estimating how many resources people, equipment, and materials a project team should use to perform project activities. The main outputs of this process are activity resource requirements, a resource breakdown structure, and project document updates. 4. Activity duration estimating Estimating activity durations involves estimating the number of work periods that are needed to complete individual activities. Outputs include activity duration estimates and project document updates. 5. Schedule development Developing the schedule involves analyzing activity sequences, activity resource estimates, and activity duration estimates to create the project schedule. Outputs include a project schedule, a schedule baseline, schedule data, and project document updates. 6. Schedule control Controlling the schedule involves controlling and managing changes to the project schedule. Outputs include work performance measurements, organizational process assets updates, change requests, project management plan updates, and project document updates.

3 1. ACTIVITY DEFINITION An activity or task is an element of work normally found on the work breakdown structure (WBS) that has an expected duration, a cost, and resource requirements. The main outputs of this process are an activity list, activity attributes, and milestone list. 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. An activity list is a tabulation of activities to be included on a project schedule. The list should include: The activity name An activity identifier or number A brief description of the activity Activity attributes provide more information about each activity, such as predecessors, successors, logical relationships, leads and lags, resource requirements, constraints, imposed dates, and assumptions related to the activity. A milestone is a significant event that normally has no duration. It often takes several activities and a lot of work to complete a milestone. Milestones are useful tools for setting schedule goals and monitoring progress. Examples include completion and customer sign-off on key documents and completion of specific products. 2. ACTIVITY SEQUENCING After defining project activities, the next step in project time management is sequencing them or determining their dependencies. Inputs to the activity sequencing process include the activity list and attributes, project scope statement, milestone list, and organizational process assets. It involves evaluating the reasons for dependencies and the different types of dependencies. A dependency or relationship relates to the sequencing of project activities or tasks.

4 Network Diagrams Network diagrams are the preferred technique for showing activity sequencing. A network diagram is a schematic display of the logical relationships among, or sequencing of, project activities. Some people refer to network diagrams as project schedule network diagrams or PERT charts. Two main formats are the arrow and precedence diagramming methods. Sample Activity-on-Arrow (AOA) Network Diagram for Project X Note the main elements on this network diagram. The letters A through J represent activities with dependencies that are required to complete the project. These activities come from the WBS and activity definition process described earlier. The arrows represent the activity sequencing or relationships between tasks. For example, Activity A must be done before Activity D; Activity D must be done before Activity H, and so on. The format of this network diagram uses the activity-on-arrow (AOA) approach or the arrow diagramming method (ADM) a network diagramming technique in which activities are represented by arrows and connected at points called nodes to illustrate the sequence of activities. A node is simply the starting and ending point of an activity. The first node signifies the start of a project, and the last node represents the end of a project. Arrow Diagramming Method (ADM) Assuming you have a list of the project activities and their start and finish nodes, follow these steps to create an AOA network diagram:

5 1. Find all of the activities that start at Node 1. Draw their finish nodes, and draw arrows between Node 1 and each of those finish nodes. 2. Put the activity letter or name on the associated arrow. 3. If you have a duration estimate, write that next to the activity letter or name, as shown in Figure above. For example, A = 1 means that the duration of Activity A is one day, week, or other standard unit of time. Also be sure to put arrowheads on all arrows to signify the direction of the relationships. 4. Continue drawing the network diagram, working from left to right. Look for bursts and merges. Bursts occur when two or more activities follow a single node. A merge occurs when two or more nodes precede a single node. For example, in Figure, Node 1 is a burst since it goes into Nodes 2, 3, and 4. Node 5 is a merge preceded by Nodes 2 and Continue drawing the AOA network diagram until all activities are included on the diagram. 6. As a rule of thumb, all arrowheads should face toward the right, and no arrows should cross on an AOA network diagram. You may need to redraw the diagram to make it look presentable. 3. ACTIVITY RESOURCE ESTIMATING Before you can estimate the duration for each activity, you must have a good idea of the quantity and type of resources (people, equipment, and materials) that will be assigned to each activity. The nature of the project and the organization will affect resource estimating. 4. ACTIVITY DURATION ESTIMATING After working with key stakeholders to define activities, determine their dependencies, and estimate their resources, the next process in project time management is to estimate the duration of activities. Duration includes the actual amount of time worked on an activity plus the elapsed time. Effort is the number of workdays or work hours required to complete a task. Effort does not normally equal duration.

6 People doing the work should help create estimates, and an expert should review them. Do not confuse duration with effort, which is the number of workdays or work hours required to complete a task. A duration estimate of one day could be based on eight hours of work or eighty hours of work. Duration relates to the time estimate, not the effort estimate. 5. SCHEDULE DEVELOPMENT Schedule development uses the results of all the preceding project time management processes to determine the start and end dates of the project. The ultimate goal of developing the schedule is to create a realistic project schedule that provides a basis for monitoring project progress for the time dimension of the project. The main outputs of this process are the project schedule, a schedule baseline, project document updates, and schedule data. Some project teams create a computerized model to create a network diagram, enter resource requirements and availability by time period, and adjust other information to quickly generate alternative schedules. Several tools and techniques assist in schedule development: A Gantt chart is a common tool for displaying project schedule information. Critical path analysis is a very important tool for developing and controlling project schedules. Critical chain scheduling is a technique that focuses on limited resources when creating a project schedule. PERT analysis is a means for considering schedule risk on projects. Gantt Charts Gantt charts provide a standard format for displaying project schedule information by listing project activities and their corresponding start and finish dates in a calendar format. Symbols include: Black diamonds: Milestones

7 Thick black bars: Summary tasks Lighter horizontal bars: Durations of tasks Arrows: Dependencies between tasks Sample Gantt chart for Software Launch Project Critical Path Method (CPM) Many projects fail to meet schedule expectations. Critical path method (CPM) also called critical path analysis is a network diagramming technique used to predict total project duration. A critical path for a project is the series of activities that determines the earliest time by which the project can be completed. The critical path is the longest path through the network diagram and has the least amount of slack or float. Slack or float is the amount of time an activity can be delayed without delaying a succeeding activity or the project finish date.

8 Calculating the Critical Path Develop a good network diagram. Add the duration estimates for all activities on each path through the network diagram. The longest path is the critical path. If one or more of the activities on the critical path takes longer than planned, the whole project schedule will slip unless the project manager takes corrective action. Determining the Critical Path for Project X Program Evaluation and Review Technique (PERT) Another project time management technique is the Program Evaluation and Review Technique (PERT) PERT is a network analysis technique used to estimate project duration when there is a high degree of uncertainty about the individual activity duration estimates. PERT uses probabilistic time estimates: Duration estimates based on using optimistic, most likely, and pessimistic estimates of activity durations, or a three-point estimate. PERT weighted average = optimistic time + 4X most likely time + pessimistic time 6

9 Example: PERT weighted average = 8 workdays + 4 X 10 workdays + 24 workdays 6 = 12 days where: optimistic time= 8 days most likely time = 10 days pessimistic time = 24 days Therefore, you d use 12 days on the network diagram instead of 10 when using PERT for the above example. Example: Activities Predecessor Duration Estimation (weeks) Expected Duration Optimistic Likely Pessimistic A B A C A D A E B, C F E CONTROLLING THE SCHEDULE The final process in project time management is controlling the schedule. Like scope control, schedule control is a portion of the integrated change control process under project integration management. 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 they occur.