What is Usability?

Good Usability is a Requirement for World Class Health Information Technology (HIT) Systems

World class systems are composed of hardware that has been carefully tested for performance and reliability. Software, which too has been carefully tested for performance and reliability, is installed on this hardware. To this we add something whose performance and reliability are among the most difficult things to predict: the human factor.

Healthcare providers, patients, and payors embody the human factors that are critical to healthcare.

Usability is a measure of the performance and reliability for systems that include human factors. Specifically, usability is the effectiveness, efficiency with which specified users achieve specified goals in particular environments. In addition, usability is concerned with the users' evaluations of the systems they use.

bullseye Effectiveness -The accuracy and completeness with which goals are achieved.
fast greyhound Efficiency - The resources expended in relation to the accuracy and completeness of goals achieved.
happy dance Satisfaction - The comfort and acceptability of the work system to its users and other people affected by its use.

How do you design for good usability?

Good usability results from the user-centered design process.

To ensure products have good usability, designers use what's known as "user-centered design." This processes takes the perspective of the product's user from the very beginning of the design process.

Before screens or databases are designed, the users and their tasks have to be thoroughly understood. Usability analysts call this "user research" and it starts with learning about the training and experience of the users. Then the analysts conduct research to determine how users go about completing their tasks and how the users' environment may affect their task.

The sequencing of tasks, steps & information required to complete tasks, criticality and frequency, as well as interactions required with other users, must be documented before a suitable product can be designed. Understanding the users' goals at each step in their processes and workflows is a major part of "user research."

Once the users, tasks, & their environment are understood, usability analysts apply current knowledge from the fields of human factors engineering, cognitive psychology, and industrial design to create a prototype of a product that should meet the users' needs.

This prototype is shared with users to gather their feedback and may be used in "formative" (i.e., early) usability testing. Several interations of prototypes, user feedback, and redesign are often used to refine the product. Testing should be started early in the development cycle to ensure that design changes can be made before the product is sold to customers.

How is Usability Measured?

Usability testing is necessary to measure usability.

Users' impressions of usability after merely looking at a product can often be unreliable. Users must be observed actually using products to determine if the products have adequate usability. Usability tests are conducted to gather observational data on usability. Many different measures related to performance & user satisfaction can be collected during a usability test. Here are several examples:

  • A good effectiveness measure is the number of tasks successfully completed by users in a reasonable amount of time time.
  • A good efficiency measure is the ratio of productive time (i.e., time spent completing tasks) to unproductive time (i.e., time spent recovering from errors or searching/asking for help).
  • A good measure of user satisfaction would be a user's willingness to recommend the new system to colleagues.
Keep in mind though, that if usability tests are to be valid, they must be designed to gather the results in the proper context. This context consists of:
  • The users who must be the same kind of users as the product's target audience. Users' experience with their domain (e.g., internal medicine) and technology must be like that of the target audience.
  • The tasks the users are to perform during the usability test must the same tasks the target audience would be expected to perform, e.g., look-up a patient's history.
  • The environment in which the usability test is conducted must be similar to the environment in which the new technology will be used. For example, if hospitals are crowded and noisy, the usability test must try to simulate those conditions.