Part 201: Basis of Estimates
(OUTPUT Project Schedule Management: Estimate Activity Durations)
(OUTPUT Project Cost Management: Estimate Costs)
(OUTPUT Project Resource Management: Estimate Activity Resources)

  • The Basis of Estimates provides justification for our estimate (Cost and Duration)
  • While amount and level of detail depends on application, it should clearly show how the estimate was derived
  • Supporting details include
    • Basis of estimate
    • Assumptions made
    • Known constraints
    • Range of possible estimates
    • Confidence level in final estimate
    • The specific risks that influenced our estimate
  • For example
    • It will take two weeks to install 10,000 square feet of grass
    • Each day, we can install 1,000 square feet of grass (as determined in a previous project)
    • The labor cost is $1,000 per day
    • That means it will take ten days of labor to install the grass, and cost us $10,000
    • We assume that the grass, tools, and equipment will be available
    • We assume that the labor is available
    • There is a risk that it will rain for up to six days, and we can’t install grass when the ground is wet
    • Then the range is 10 to 16 days, and we are 90% confident in our estimate