RollUp of Estimates

Using experience to size a project from the top down has value because it can be done early in the project when only general knowledge about the physical design is available. Function point counting, however, is based on physical information about files, inputs, and outputs.

The most reliable method of estimating, although the most time-consuming, is to make an estimate for each piece of work jointly with the team member who is responsible for it and to combine the estimates from the bottom up. Bottom-up estimating involves answering three questions:

â–  How long will they take to complete? (Detailed estimates can be imposed on or negotiated with employees.)

A project leader talented in informal project management can negotiate tight but achievable estimates as well as obtain personal commitment from the staff members. Firm commitment can only be made once the design is known at least in outline form.

Top-down estimates are made early in a project, done cheaply, and often changed. Bottom-up estimates are set, costly to produce, and established later in a project.

Jones, Applied Software Measurement, New York: McGraw-Hill, 1991.

Project Management Made Easy

Project Management Made Easy

What you need to know about… Project Management Made Easy! Project management consists of more than just a large building project and can encompass small projects as well. No matter what the size of your project, you need to have some sort of project management. How you manage your project has everything to do with its outcome.

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