CS 305: Interface Evaluation and Critique


Highlights of this lab:

  • The Good, Bad, and The Ugly of Lyx (Quick Discussion)
  • Usability Defined
  • Usability Inspection
  • Assignment

:: In-Class Exercise ::

In this part of the lab we will discuss your experiences using Lyx (from your first lab)


:: Usability Defined ::

What is Usability?

Usability addresses the relationship between tools and their users. When using tools, there 3 possible stages of usability could include:

For a tool to be satisfying, it must provide the best possible mapping between the task that the tool is supposed to help accomplish and the users view of how to best accomplish the task (Norman). For example:

Usability refers to the quality of a tool, that whcih makes it easy to learn, easy to use, easy to remember, error tolerant, and subjectively satisfying.

The same principle applies to the software, and hardware for that matter, that we create.

What makes software usable?

By learning design principles and design guidelines we designers can produce better tools. Understanding the users and the task is key. Even the most insightful designer can only create a highly-usable system through a process that involves getting information from the people who are actually going to use the tool.

Why is Usability Important?

The importance of usability is tenfold. Usable software makes the user's experiences more satisfying thus provides everyone with the greatest benefit

In all cases, lack of usability can cost time and effort, and can greatly determine the success or failure of a system. Given a choice, people will tend to buy systems that are more user-friendly.

Achieving Usability

The first steps in acheiving usability is to employ iterative design, which progressively refines the design through evaluation from the early stages of design. In your class and in the next lab we will be discussing Scenario-based engineering, a highly iterative process.

Adhering to the laws of user interface design. (Raskin)

  1. A computer shall not harm your work or, through inaction, allow your work to come to harm.
  2. A computer shall not waste your time or require you to do more work than is strictly necessary
  3. An interface is humane if it is responsive to human needs and considerate of human frailties.
  4. User's should set the pace of an interaction.

In this lab, we are going to focus on a formal method to evaluate, from a designers or experts point of view, software systems. This method is referred to as Heuristic Evaluation.


:: Usability Inspection ::

Usability inspection refers to a set of techniques and methods for evaluating user interfaces through examination or critique as opposed to user testing of the interface. The critique is normally based on the "critiquer's" experience, or a set of psychological principles pre-defined guidelines. One such technique, or set of guidlines is called Heuristic Evaluation.

Heuristic Evaluation

Heuristic Evaluation is a technique for finding usability problems with a user interface. A small group of experts, usually 3 to 5 experts, separately analyize a user interface using a pre-defined set of "heuristics", i.e. broad guidelines that are generally relevant to the task and the system. They then combine their results and rank the importance of each problem to prioritize fixing them. Nielsen identified 10 heuristics which are broadly helpful in spotting the majority of problems (verbatim from Neilson's website):

  1. Visibility of system status: The system should always keep users informed about what is going on, through appropriate feedback within reasonable time.
  2. Match between the system and the real world: The system should speak the users' language, with words, phrases and concepts familiar to the user, rather than system-oriented terms. Follow real-world conventions, making information appear in a natural and logical order.
  3. User control and freedom: Users often choose system functions by mistake and will need a clearly marked "emergency exit" to leave the unwanted state without having to go through an extended dialogue. Support undo and redo.
  4. Consistency and standards: Users should not have to wonder whether different words, situations, or actions mean the same thing. Follow platform conventions.
  5. Error prevention: Even better than good error messages is a careful design which prevents a problem from occurring in the first place. Either eliminate error-prone conditions or check for them and present users with a confirmation option before they commit to the action.
  6. Recognition rather than recall: Minimize the user's memory load by making objects, actions, and options visible. The user should not have to remember information from one part of the dialogue to another. Instructions for use of the system should be visible or easily retrievable whenever appropriate.
  7. Flexibility and efficiency of use: Accelerators -- unseen by the novice user -- may often speed up the interaction for the expert user such that the system can cater to both inexperienced and experienced users. Allow users to tailor frequent actions.
  8. Aesthetic and minimalist design: Dialogues should not contain information which is irrelevant or rarely needed. Every extra unit of information in a dialogue competes with the relevant units of information and diminishes their relative visibility.
  9. Help users recognize, diagnose, and recover from errors: Error messages should be expressed in plain language (no codes), precisely indicate the problem, and constructively suggest a solution.
  10. Help and documentation: Even though it is better if the system can be used without documentation, it may be necessary to provide help and documentation. Any such information should be easy to search, focused on the user's task, list concrete steps to be carried out, and not be too large.

:: Assignment ::

For this lab assignment I would like you all to provide a heuristic evaluation based on the above 10 criteria. The system I want you to evaluate is Microsoft Word. I would like you to evaluate Word when creating a simple document similar to that which you did last lab using Lyx. This assignment is meant to assist you in understanding how to evaluate the usability of software and to get you thinking about your project.

For additional resources of how to conduct a heuristic evaluation, you may click here:

Note: I would like you to use the above example and the 10 heuristics as outlined by Neilson (above) to guide your evaluation. Your evaluation does not have to be as long as the provided example in the link above but to get full marks, you must show that some effort was used (just keep that in mind! ;-)

This lab assignment is due by Thursday, Sept. 29 at 12:00pm. Hand in your document (MS Word or whatever text editor you use) using web-ct. The assignment will be available in the "Assignments" folder.


:: Online Source(s) ::