User Story Based Estimation

The #user #story based #estimation model uses user stories as the unit of estimation and considers user story factors such as requirements complexity, solution components, external interfaces, and quality attribute complexity to arrive at the overall estimate.

Step 1: Define the Attributes of the User Story

Each user story should be validated to ensure that the user story attributes are defined in detail to ensure accurate usage of the estimation model. Here is a generic set of attributes used:

• #Requirements complexity: This attribute indicates the complexity of the user story requirement. If the requirement involves complex business rules or has complex flow steps, it is considered highly complex.
• #Solution #components: This attribute indicates the number of solution components that will be developed to implement the user story.
• #External #interfaces: The attribute provides a list of external integrations needed to implement the user story. The complexity increases with an increase in the number of external interfaces.
• #Quality #attribute complexity: This attribute indicates the non-functional requirements such as #performance, #scalability, and #modularity needed.

Based on the scenarios and user story needs, you may also include other attributes such as #test #case complexity, #technology complexity, #business #transaction complexity, and #data volume in the list of attributes.

Step 2: Define the Estimation Guidelines for Story Attributes

In this step, you define the estimation categories needed for the user story and define the qualification criteria for each of the estimation attributes.

You then give a value to the #effort of each of the estimation categories in person days or story point: (simple 4h), (medium 1d), (complex 3d) ...

You can use the historical #analysis of the effort value for similar user stories in past projects. Some of the attributes get more weight based on their importance to the user story.

Step 3: Estimate Each User Story

Once the user story estimation model is ready, the #project #manager can use this model to estimate each user story.

The overall effort will be a weighted sum of story attributes for each of the user stories. The value can then be used for #costing and #staffing purposes.

Step 4: Validate and Fine Tune Estimation Guidelines

At the end of the user story execution, the project manager compares the #estimated effort values to the #actual effort spent. The difference indicates the #error #margin. The project manager has to continuously update the effort guidelines based on this analysis.