Usability Methods Explained: Scenarios of Use – Part 2

This blog post is the second in a series of two about scenarios of use as a usability method.

How to generate scenarios of use

Scenarios of use are not exceptionally difficult to craft, which makes them an attractive usability method.  Creating them, however, is easiest if you have a facilitator with strong communication and interpersonal skills—this helps boost group morale and creates an atmosphere that has a higher level of productivity.  When creating your scenarios of use, try to generate a number of scenarios that cover a wide range of circumstances, both positive and negative (the negative are called ‘misuse cases’).  You want to be sure to include misuse cases so you can investigate non-functional requirements such as the security and accessibility of your interface design.  You should go through all scenarios of use by yourself or with your group before you include stakeholders.

What are the 8 steps to developing scenarios of use?

According to Edward Kenworthy’s 1997 book Use Case Modeling: Capturing User Requirements the eight steps to developing scenarios of are:
1. Identify who is going to be using the website (this also works for other web-based, desktop-based or mobile applications).
2. Pick one of those actors.
3. Define what that actor wants to do on the site. Each thing the actor does on the site becomes a scenario of use.
4. For each scenario of use, decide on the normal course of events when that actor is using the site.
5. Describe the basic course in the scenario of use. Describe it in terms of what the actor does and what the system does in response that the actor should be aware of.
6. When the basic course is described, consider alternate courses of events and add those to “extend” the scenario of use.
7. Look for commonalities among the scenarios of use. Extract these and note them as common course scenario of use.
8. Repeat the steps 2 through 7 for all other actors.

What are the limitations of scenarios of use?

According to Alistair Cockburn, scenarios of use are an indispensable usability method, but they do not “take care of system design, user interface design, feature lists, or testing”.  Thus, scenarios of use can only assist you in laying the foundation for a great user interface design; scenarios of use help you hypothesize about your interface design, but they do not aid you in the actual feature design or edits of your prototype. Scenarios of use provide guidelines and suggestions only, but are still very useful because they help you identify the points in your interface design upon which you should focus design effort and subsequent usability tests.