RASS Estimate - Use Case model

Use Cases Sizing based Estimation model

For further details you can download these references: MS Word document MS PowerPoint Presentation

Use Cases are a popular way to specify the functionalities of a software system specifically for object oriented development. Use Cases provide a good basis for estimating software projects. RASS Estimate has included an Estimation model based on the sizing of Use Cases. This estimation model falls in the category of software estimation methods that use Function Points as a size measure of software functionality from user perspective. The method to size the Use Cases is called “Use Case Points” calculation method. A Use Case Point represents a unit of the size of software functionality. The method to calculate the Use Case Points uses the functional requirements written as Use Cases for a software system being developed or modified.

The main features of Use Case Sizing based Estimation model include:

Creating the Breakdown Structures of requirements or Use Cases

Choices of Use Case Sizing methods:

Mannual counting of Use Case Points if the Use Cases are available for counting
Estimating of Use Case Points if Use Cases are not yet written and only high level requirements are available

Choice of using Estimation methods

Productivity Rate based Bottom-Up approach if Productivity Rate (hours per Use Case Point) is available.
COCOMO-II based Top-Down Estimation approach if Source Lines of Code (SLOC) per Use Case Point is available.

This model can display side by side the effort estimates from COCOMO and the Productivity methods. However, only the configured method is linked to Estimation Reports.
Domain profiles based on historical data are used for estimating Use Case Points
Productivity rates are associated with domain profiles
Outsource Supplier Estimates are based on Outsoource profiles. Outsource Profiles are centrally defined and maintained.
All functionalities available in the model have been implemented on one screen.
Calculation of Schedule Estimate is based the combined effort estimates from all estimation models used by the project
Estimation Reports are based on integrated estimates.

The graphics on the left side shows high level users' view of this estimation model.

The selection of the choice of estimation method is done during the creation of the estimation project. However, you can change it any time. The selected estimation method is tied up with estimation reports. Estimates from other methods are available for viewing only.

The choice of sizing method is not configured but is execised at the time of entering the estimation data. Be careful here as your counting data will be overwritten if you execute the "Estimate Size" action button.

The most critical part of this model is the creation of Domain Profiles, Outsource Profiles and the programming language table. The programming language table is used only if COCOMO method is selected. Productivity Rates are maintained in Domain Profiles.

RASS Estimate includes preconfigured generic Estimation Projects which can be used to tailor new estimation projects thereby reducing the model configuration tasks to a minimum level.

The model is easy to use. Action buttons are used to perform various tasks.

To give you a feel of this estimation model, the following is a screen shot showing various building blocks of this estimation model.

Further details of this estimation model are available in a MS Power Point Presentation and a MS Word document

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