Activity Resource Estimating: Inputs

.3 Parametric Estimating Estimating the basis for activity durations can be quantitatively determined by multiplying the quantity of work to be performed by the productivity rate. For example, productivity rates can be estimated on a design project by the number of drawings times labor hours per drawing, or a cable installation in meters of cable times labor hours per meter. The total resource quantities are multiplied by the labor hours per work period or the production capability per work period, and divided by the number of those resources being applied to determine activity duration in work periods. .4 Three-Point Estimates The accuracy of the activity duration estimate can be improved by considering the amount of risk in the original estimate. Three-point estimates are based on determining three types of estimates: • Most likely. The duration of the schedule activity, given the resources likely to be assigned, their productivity, realistic expectations of availability for the schedule activity, dependencies on other participants, and interruptions. • Optimistic. The activity duration is based on a best-case scenario of what is described in the most likely estimate. • Pessimistic. The activity duration is based on a worst-case scenario of what is described in the most likely estimate. An activity duration estimate can be constructed by using an average of the three estimated durations. That average will often provide a more accurate activity duration estimate than the single point, most-likely estimate. .5 Reserve Analysis Project teams can choose to incorporate additional time referred to as contingency reserves, time reserves or buffers, into the overall project schedule as recognition of schedule risk. The contingency reserve can be a percentage of the estimated activity duration, a fixed number of work periods, or developed by quantitative schedule risk analysis Section 11.4.2.2.. The contingency reserve can be used completely or partially, or can later be reduced or eliminated, as more precise information about the project becomes available. Such contingency reserve is documented along with other related data and assumptions.

6.4.3 Activity Duration Estimating: Outputs

.1 Activity Duration Estimates Activity duration estimates are quantitative assessments of the likely number of work periods that will be required to complete a schedule activity. Activity duration estimates include some indication of the range of possible results. For example: • 2 weeks ± 2 days to indicate that the schedule activity will take at least eight days and no more than twelve assuming a five-day workweek. • 15 percent probability of exceeding three weeks to indicate a high probability—85 percent—that the schedule activity will take three weeks or less. A Guide to the Project Management Body of Knowledge PMBOK ® Guide Third Edition 142 2004 Project Management Institute, Four Campus Boulevard, Newtown Square, PA 19073-3299 USA .2 Activity Attributes Updates The activity attributes Section 6.1.3.2 are updated to include the durations for each schedule activity, the assumptions made in developing the activity duration estimates, and any contingency reserves.

6.5 Schedule Development

Project schedule development, an iterative process, determines planned start and finish dates for project activities. Schedule development can require that duration estimates and resource estimates are reviewed and revised to create an approved project schedule that can serve as a baseline against which progress can be tracked. Schedule development continues throughout the project as work progresses, the project management plan changes, and anticipated risk events occur or disappear as new risks are identified. 6 Figure 6-9. Schedule Development Overview: Inputs, Tools Techniques, and Outputs

6.5.1 Schedule Development: Inputs

.1 Organizational Process Assets The organizational process assets Section 4.1.1.4 of the performing organization may have some asset items that can be used in Schedule Development, such as a project calendar a calendar of working days or shifts that establishes dates on which schedule activities are worked, and nonworking days on which schedule activities are idle. .2 Project Scope Statement The project scope statement Section 5.2.3.1 contains assumptions and constraints that can impact the development of the project schedule. Assumptions are those documented schedule-related factors that, for schedule development purposes, are considered to be true, real, or certain. Constraints are factors that will limit the project management team’s options when performing schedule network analysis. There are two major categories of time constraints considered during schedule development: A Guide to the Project Management Body of Knowledge PMBOK ® Guide Third Edition 2004 Project Management Institute, Four Campus Boulevard, Newtown Square, PA 19073-3299 USA 143