Project Management: Assumptions (Definitions)

"When used in a Business Case, forecast, or other planning document, an assumption is a statement that relates to a potential future state or future situation." (Steven Haines, "The Product Manager's Desk Reference", 2008)

"Assumptions are factors that, for planning purposes, are considered to be true, real, or certain without proof or demonstration." (Cynthia Stackpole, "PMP® Certification All-in-One For Dummies®", 2011)

"Hypothesis, belief, or conjecture made when something is not known with certainty. In cost accounting, assumptions exist for the various quantitative analysis techniques (e.g., CVP or regression analysis) and general quantitative decision rules (e.g., for product emphasis decisions). People also make assumptions to create cost accounting information (e.g., linear cost function). Poor quality assumptions lead to poor quality information and decisions. Failure to objectively analyze assumptions can lead to biased decisions." (Leslie G Eldenburg & Susan K Wolcott, "Cost Management" 2nd Ed, 2011)

"A condition that will affect the project, although the specifics of the condition are not yet known. For the purposes of planning, the specifics are assumed and called out as an assumption." (Bonnie Biafore & Teresa Stover, "Your Project Management Coach: Best Practices for Managing Projects in the Real World", 2012)

"Hypotheses regarding the conditions necessary for the realization of strategies over which the organization has no control. Assumptions represent the risks that you may not achieve desired outcomes. Any change to an assumption during the execution cycle should force a revision." (Paul C Dinsmore et al, "Enterprise Project Governance", 2012)

"Something that is taken for granted to be true." (Joan C Dessinger, "Fundamentals of Performance Improvement" 3rd Ed, 2012)

"A factor in the planning process that is considered to be true, real, or certain, without proof or demonstration." (For Dummies, "PMP Certification All-in-One For Dummies" 2nd Ed., 2013)

"Something presumed to be true. Assumptions are the basis of all statistical analysis. (It is important that the analyst choose methods based only on assumptions that are reasonable for the application.)" (Meta S Brown, "Data Mining For Dummies", 2014)

"An assumption is something that is taken for granted or unquestionably accepted as true." (Ken Sylvester, "Negotiating in the Leadership Zone", 2015)

"A factor in the planning process that is considered to be true, real, or certain, without proof or demonstration." (Project Management Institute, "A Guide to the Project Management Body of Knowledge (PMBOK® Guide)", 2017)

"Unproven business supposition used to make rapid progress toward a conclusion." (Pamela Schure & Brian Lawley, "Product Management For Dummies", 2017)

"An effort estimate is not complete without including its assumptions. Estimate assumptions include any and all underlying factors the estimate relies upon. Assumptions are especially important in more rigid estimation environments, but they are a good practice even where expectations are more flexible. Explicitly listing all assumptions helps to remove ambiguity and avoid misunderstandings during project delivery." (Morgan Evans, "Engineering Manager's Handbook", 2023)