: process of forecasting or approximating the time (days, weeks, months) and cost ($, staff hours, staff
days, capital, labor) of completing project deliverables. Task of balancing the expectations of stakeholders and the
need for control while the project is implemented.
Types of estimates:
Top down (macro): analogy uses factored cost of previous similar projects), group consensus, or mathematical
Bottom up (micro): estimates elements of the work break down structure.
parametric: data and experienced based
Range: estimate range of time expected to complete the task, pessimistic, optimistic, likely
Quality of estimates effect
Decisions, work schedule, project duration and cost, cash flow, whether the project is worth pursuing, measurement
in project performance, baseline
Factors influencing quality of estimates:
planning horizon: activities closer are more accurate, while those further out have more uncertainty
project duration: longer projects are less accurate. Especially with rapid changes in technology
People: Skills of estimator, skill of team members, new team members add uncertainty, synergy
Project structure and organization: Dedicated team (efficient) vs matrix team (lower cost more time)
Padding estimates: padding raises cost and decreases accuracy (risk should be manged separately)
Organizational culture: culture preference (time, cost, estimate specifications)
Other: holiday, vacation, resources, funds, equipment
Have people familiar with task make estimate (
subject mater experts: SME
Use multiple people to make estimates (larger sample size more certainty)
Base estimates on normal conditions, efficient methods, and normal level of resource.
Use consistent time units in estimating task times