Chapter 3 - Short Answer

Identify, in order, the six steps basic to both PERT and CPM.

1. Define the project and prepare the WBS. 2. Develop the relationships among the activities. 3. Draw the network connecting all of the activities. 4. Assign the time and/or cost estimates to each activity. 5. Compute the critical path—the longest time path through the network. 6. Use the network to help plan, schedule, monitor, and control the project.

What are some of the ethical issues faced by project managers? Which of these are likely to occur before a project begins, which are likely to occur while the project is underway, and which may occur after a project is complete? Illustrate any one of these from recent news.

A project manager, trying to select firms to undertake a project, might be exposed to bid rigging, low balling, or bribery on the part of firms competing for business. Once a project is underway, expense account padding, use of substitute (substandard) materials, or ignoring regulatory requirements are possible. Those who report on completed projects might not be truthful about the project's success (consider the massive changes that took place at NASA after two shuttle disasters, and note the very recent failure of the FBI's Carnivore software)

What is a project organization?

A project organization is a form of management so that people and other resources are pooled for a limited amount of time to complete a specific goal or project.

Describe in words how to calculate a project's standard deviation. What assumption allows that calculation to be accurate?

Add the variances of the activities on the critical path and then take the square root. We can do this because we assume that the activities are independent.

Briefly describe the concept of cost/time trade-off and how it is used.

Cost/time trade-off is fundamentally PERT with additional information provided that enables one to monitor and control project cost and to study possible cost/time trade-offs. This can be done by making a budget for the entire project using the activity cost estimates and by monitoring the budget as the project takes place. Using this approach, we can determine the extent to which a project is incurring a cost overrun or a cost underrun. In addition, we can use the same technique to determine the extent to which a project is ahead of schedule or behind schedule.

What is the objective of critical path analysis?

Critical path analysis determines the longest path through a network of activities. This longest path is the key to making the schedule that provides for completing all activities in the shortest time. Critical path analysis identifies those activities critical to timely completion of all activities so they can receive management focus.

Explain why the critical path is the longest, not the shortest, path through a network.

Critical path is that set of activities in a project network that controls the duration of the entire project. The controlling element to completion of all activities is the longest path; any shorter path will not allow for all activities to be completed.

Identify and describe briefly each of the purposes of project scheduling.

It shows the relationship of each activity to others and to the whole project. It identifies the precedence relationship among activities. It encourages the setting or realistic time and cost estimates for each activity. It helps make better use of people, money, and material resources by identifying critical bottlenecks in the project.

Describe some of the challenges faced in the construction of the new 11-story building at Arnold Palmer Hospital in Orlando, Florida.

Prior to beginning actual construction, regulatory and funding issues added, as they do with most projects, substantial time to the overall project. Cities have zoning and parking issues, the EPA has drainage and waste issues, and regulatory authorities have their own requirements, as do issuers of bonds.

Identify the responsibilities of project managers.

Project managers are directly responsible for making sure that (1) all necessary activities are finished in proper sequence and on time; (2) the project comes in within budget; (3) the project meets its quality goals; and (4) the people assigned to the project receive the motivation, direction, and information needed to do their jobs.

Define slack.

Slack is the amount of time an activity can be delayed without delaying the entire project, assuming its preceding activities are completed as early as possible.

PERT calculations typically include the duration variance of each activity. What is the purpose of this calculation—what's the role of variances in PERT analysis?

The activity variances influence the probability of project completion. Specifically, the sum of the variances of the critical tasks equals the variance of the project. Further, large variances on noncritical tasks need to be monitored. Such an activity might have an actual completion time so large that the task becomes a critical task.

What are the advantages of using PERT and CPM?

The advantages include its usefulness for scheduling and controlling large projects, its straightforward concept, its graphical displays of relationships between activities, its critical path and slack time analysis, its ability to document processes, its wide range of applicability, and its usefulness in monitoring schedules and costs.

What is the basic difference between PERT and CPM?

The basic difference between PERT and CPM is that PERT requires three time estimates of activity completion time, whereas CPM uses only a single estimate.

Briefly discuss what is meant by critical path analysis. What are critical path activities and why are they important?

The critical path consists of those tasks that determine the overall project completion time (or that will delay the completion of the project if they are delayed); these must be managed most closely to ensure timely completion of the project. Critical path analysis is the determination of which task elements are on, or likely to be on, the critical path (the longest path through the network).

Describe the differences between a Gantt chart and a PERT/CPM network.

The differences between a Gantt chart and a PERT/CPM network are mainly that PERT/CPM has the ability to consider precedence relationships and interdependence of activities.

What are the earliest activity start time and latest activity start time, and how are they computed?

The earliest start time is the earliest time at which an activity may start and still satisfy all precedence requirements. The latest start time is the latest time at which an activity may start and still satisfy both precedence requirements and the overall project completion time.

How is the expected completion time of a project activity, and of a PERT project, computed?

The expected completion time of a project activity uses the Beta distribution; expected time is the weighted average of optimistic, most likely, and pessimistic time estimates. Expected completion of a PERT project is the sum of the expected times for individual activities that are on the critical path.

What are the three phases of a project? Describe each in a sentence or two.

The three phases are planning, scheduling, and controlling. Planning includes goal setting, defining the project, and team organization. Scheduling relates people, money, and supplies to specific activities and relates activities to each other. Controlling is where the firm monitors resources, costs, quality, and budgets. It also revises or changes plans and shifts resources to meet time and cost demands.