Establish and maintain estimates of work product and task attributes.

Size is the primary input to many models used to estimate effort, cost, and schedule. Models can also be based on other attributes such as service level, connectivity, complexity, availability, and structure.

Estimation methods include using historical acquirer and supplier data and standard estimating models to compare projects of similar complexity. Where historical size data are not available, develop an estimate based on the understanding of the design of similar products.

Estimation models can be built based on historical data as part of organizational process performance, and estimates for any project can be validated using these models.

Refer to the Organizational Process Performance process area for more information about establishing process performance models.

The estimates should be consistent with project requirements to determine the project’s effort, cost, and schedule. A relative level of difficulty or complexity should be assigned for each size attribute.

Example Work Products

1.    Size and complexity of tasks and work products

2.    Estimating models

3.    Attribute estimates

4.    Technical approach

Subpractices

1.    Determine the technical approach for the project.

The technical approach defines a top-level strategy for development of the product. It includes decisions on architectural features, such as distributed or client/server; state-of-the-art or established technologies to be applied, such as robotics, composite materials, or artificial intelligence; and the functionality and quality attributes expected in the final products, such as safety, security, and ergonomics.

The technical approach provides a basis for interoperability and supportability of the technical solution developed by the supplier. The technical approach is often developed as part of and included in the acquisition strategy.

2.    Use appropriate methods to determine the attributes of the work products and tasks to be used to estimate resource requirements.

Methods for determining size and complexity should be based on validated models or historical data.

The methods for determining attributes evolve as the understanding of the relationship of product characteristics to attributes increases.

3.    Estimate the attributes of work products and tasks.