Scenario-based Development

Usage scenarios, or just scenarios, are a core element of every user-centered development process. They are the missing link between the requirements and the design of a new solution. A scenario is basically a realistic example of how a user is going to interact with the planned system. A specific course of events is described from the user’s point of view, preferably in plain words or in the form of a listing. Content-related relevance is far more important than formal correctness.

Scenarios are based on the requirements for the new system; they can be developed iteratively or in workshop in cooperation with the users. An important advantage of a scenario is that they’re easily understandable: they can be checked, complemented or corrected from early on by different groups of entities like the employers, users and developers. In other words: in creating scenarios, the analyst models the requirements for a new system.

Properties of Scenarios

They...

...are designed for a specific group of users and takes their characteristics and needs into consideration
...illustrate a specific use case
...show how the users will utilize the new software in a realistic setting
...illustrate the aspects relevant for the development of the new solution
...aren’t narrowed down to ideal situation but also covers important examples of exceptions or errors

Application of Scenarios

Scenarios can be used for different purposes and at different stages of the development of new solutions:

Elicitation and validation of requirements: reflecting on the specific example allows the clients and users to realize, check and complement the requirements in the given use case
Specification: Scenarios can illustrate appliance of the solution in a realistic context. They can grant the developers insight into the real procedures and coherences
User interface concept: design scenarios are used to describe the interaction at the user interface. The interaction is modeled and optimized in cooperation with the users; then, the developers can extract technical requirements out of the results
Usability test scenarios: scenarios can be used as a basis for evaluating a system or prototype with the help of the users. In this case, they describe the task or case that is to be solved with the help of the new system
Trainings: scenarios serve as a means of illustrating operation sequences for user trainings, and as a basis for creating the user manual

The consistency of scenario usage during all phases of the development process render them a most effective and useful instrument for the user-centered development of interactive systems.