SBD
From GSLISWiki
Scenario Based Design is a method from computer science devised to help programmers design better programs. While nearly every practitioner of SBD uses scenarios differently, the most common usage involves using scenarios as a quick way to catch major design flaws before anything has been programmed, or at least before going through the expensive and time-consuming process of usability testing. The earlier SBD is used in creating a program, the more effective it is, since once coding has begun, it is very difficult to radically reconceptualize the project (something which is often found to be needed if the design phase is not done carefully).
One of the key things to keep in mind about Scenarios is that they cannot be used to prove that something will work, or will be ideal, but they are excellent tools to rapidly identify major problems with a design conception, or with how an interface works.
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[edit] Types of SBD
Purposes for using Scenarios
- Establishing consensus
- Requirements Capture
- Communication to non-specialists
- Dealing with option complexity
Different types of Scenarios can be used for each of these purposes.
[edit] Personas
This techniques was developed by Alan Cooper, and is described in his easy and quick to read book The Inmates Run the Asylum. The way Cooper describes his use of personas, is by doing a field study of the problem domain which the program or IT system he is designing is supposed to address. For each stakeholder, he developes as many personas as it takes to describe each of the personality types which he finds will have to/want to interact with the IT system. Then, for each stakeholder he analyzes the group of personas he has created, and condenses them down to as few different personas as possible (rarely more than three), but with each persona reflecting all of the fundamentally different user types or user biases. He then fleshes out these personas, giving them a personality, and describing them using anecdotes. The design team must know these personas as well as they know their colleagues. Then, when designing the IT system, he takes the part of the system which the stakeholder will interact with, and tests it on each of the personas he has developed for that stakeholder, and using natural human intuition about how different personalities react in different situations, figures out whether the system will meet their needs and preferences or not. This allows him to test design ideas before building prototypes, and before coding, and without the expense of bringing in actual people to try each design idea out on them.
[edit] Scenarios for Rapid Prototyping
Kind of like the negative of Personas, scenarios focus more on the story and the circumstances than on the personality of the actors and how that affects the design. One way of using scenarios and personas is having a series of personas and a series of scenarios, and plugging each persona into each scenario, and seeing how they react in the scenario. This can be used both for brainstorming and developing design ideas, and for testing design ideas by creating a scenario for each design idea, and then looking at whether the story seems believable or not. Scenarios can also be used to test the size of the design space, by designing extreme scenarios of perfection and failure of the designed systems, and using intuition to figure out how likely each situation is.
[edit] Scenarios for Communication
Sometimes it is difficult for various stakeholders in a project to communicate with one another because they do not share the same vocabulary to describe things, or because they do not have certain domain-specific experience that is necessary to understand the needs of a different stakeholder. Scenarios have been found to ease these communication problems: by telling a story the domain specific experience can be demonstrated instead of needing to be logically argued for.
[edit] Scenarios for Code Mapping
[edit] Using Scenarios in a Project
The first step in using Scenarios in a project is to learn about the project. A good way to do this is to make a list of questions. Below are some questions that should get you started, but meaningful questions are usually project dependant. Probe the depths of how the project leaders conceive of how they expect the project to work, what it should accomplish, etc. Details are the most important part.
However, it is important to realize that some of these questions are equivocal, rather than uncertain. This means that determining the answer is not a matter of looking up information, but a matter of making a decision. Half of systems design is all about getting the proper decisions made, made explicit, and agreed upon. Here Scenarios can be extremely useful, not just to figure out what different decisions could be made, but also to explore the consequences of any decisions that are being made. This will greatly help avoiding bad decisions. However, it is important to realize that Scenarios are not an exhaustive technique, and will never be able to avoid all bad decisions. Instead, they are a cheap and easy method of catching major mistakes before anything has been built, before effort has been wasted, and before any commitments have been made. Other techniques are still required to have good system design.
[edit] Questions to ask Project Leaders
- What is your project trying to accomplish?
- How do you expect to accomplish this?
- How do you see the system fitting in people's work flows?
- What will be the benefit of the new system?
- Who will benefit?
- How?
When answering the above questions, Project Leaders should be encouraged to give examples. By getting them to tell and write down a story of how they envision that the system will work, you are getting them to write a Scenario.
[edit] Questions to ask Domain Experts
[edit] Other Resources for Learning About SBD
If you are interested in learning more about SBD, LIS590SBD Scenario Based Design is a class offered by Mike Twidale which covers all the different types of SBD and touches on a few other topics, such as Participatory Design, Affordance Analysis, and Cognitive Walkthroughs.
To see how Scenario Based Design can be supported by using a wiki, see the CLEANER Project portion of the Sandbox Wiki:
http://www.gslis.org/sandbox/index.php/CLEANER
Categories: Research | Research Methods | Design | HCI | Methodology | Storytelling
