ProjectEstimation

Type: Process
Sources: my practice, Niels Malotaux (see http://www.maloteaux.nl/), http://www.iit.edu/~it/delphi.html



Entry Conditions

Entry1: You need to have clear objectives.
Note: If you don't have clear objectives, you will notice in Step 4.

Summary of Steps in this Process

  1. Sit down - alone or better with one colleague - and break the work down to one or two dozens of task-chunks. List them.
  2. Distribute the list to the people who will work on the project or know enough about the work to be done. Ask for their best estimates for each chunk. Allow for adding items to the list.
  3. See where estimates differ greatly. Discuss or further define the contents, not the estimates.
  4. Iterate S2-3 until sufficient consensus is reached.
  5. Add up all task-chunk's estimates: that's how much work the project is.

Steps and Notes

S1: Sit down - alone or better with one colleague - and break the work down to one or two dozens of task-chunks. List them.
Notes:

  • If it's a well-known problem go find someone who did it before!
  • If it's a rather small project you can break it down to single tasks, but you don't have to. Roughly 10-25 list items.
  • Best effort. Don't worry too much about forgetting things or about the uncertainty because you don't know every constraint.

S2: Distribute the list to the people who will work on the project or know enough about the work to be done. Ask for their best estimates for each chunk. Allow for adding items to the list.
Notes:

  • It's a good idea to limit the time for the estimations, especially if you have external staff that is paid by time and material.
  • Don't go for ultimate precision, you won't achieve it anyway. Variances will average.
  • You're much better off with an initial, not so precise estimate and early, constant calibration.

S3: See where estimates differ greatly. Discuss or further define the contents, not the estimates.
Notes:

  • Everyone's an expert here. It is not about right or wrong estimates, but about understanding the work to be done.
  • In the original Delphi process there's an element of anonymity. I can't follow that advice, for the purpose of this process also is to build consensus.

S4: Iterate S2-3 until sufficient consensus is reached.
Notes:

  • Niels says, not more than one or two iterations are necessary.
  • I say, it sometimes needs a dictator approach.
  • Careful here, make sure to discuss the content of the work. Also helpful to further specify the objectives!

S5: Add up all task-chunk's estimates: that's how much work the project is.
Note: The single most useful approach to fitting the work in a tight schedule is to work hard to NOT do things that later will be superfluous.

Quote

All estimates are wrong. If they were right, they would be commitments.

— Unknown

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