Page 127 - DCAP304_DCAP515_SOFTWARE_PROJECT_MANAGEMENT

Unit 6: Effort Estimation

3. The ………………… should hold a brainstorming session to try to identify as many Notes
assumptions as possible.
4. Discussing and writing down the assumptions in a team setting helps the team to identify
potential…………………...
5. In project management accurate estimates are the basis of ………………….. project planning.

6.2 Problems with Estimation

How Inaccurate Estimates lead to Failed Projects

Inaccurate estimates and misconceptions about the estimating process often contribute to failed
projects.
An inaccurate estimate leads to infeasible plans. When infeasible plans are implemented, the
result is often missed deadlines, inadequate performance and/or poor quality.
Inaccurate estimation can be attributed to:

 Lack of past data on which to base estimates
 Lack of estimating experience
 Lack of a systematic estimation process, sound techniques, or models suited to the project’s
needs
 Failure to include essential project activities and products within the scope of the estimates

 Unrealistic expectations or assumptions
 Failure to recognize and address the uncertainty inherent in software estimates.

Accommodating Reuse in the Estimates
Estimates for the amount of code that can be reused are a source of error and risk in estimating
software cost. PL/PM tends to be overly optimistic about the effort that will be necessary to
adapt the existing code. They often assume only a 10% change to a program’s design and code
will be necessary when in fact the changes are often more than 50%.
Other factors that commonly contribute to size, cost and schedule risks are:
 Optimistic assessments of the software development environment and resources, and

 Misunderstood or constantly changing requirements.
The risk management should be revisited each time the project estimate is updated. The risk
management plan update should not concentrate only on the risk areas identified originally.

Example: An off-the-shelf-software package may not be performing as originally assumed.
Each time an estimate is done, the assumptions and inputs should be updated to reflect the most
current information.

Use of Past Data

Past data from the PKB and/or from the same project should be used to improve the accuracy of
the estimates.

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