Friday, July 6, 2007


A key factor in a system's success or failure.

In many ways, the human-machine interface is the most important part of any computer system. Users will invariably judge their experience with the system through the ease and convenience of using the interface. A good user experience goes a long way towards user acceptance of the system. Acceptance means users will use the system more. The more they use it, the more trust and confidence in the system grows. Soon enough, users will rely on it. Contrast that with an unwieldy and poorly designed interface. The backside of this second system might be more powerful than the first but if its interface is unwieldy and poorly designed and most users have a negative experience, it will be difficult for the system to be accepted.

User acceptance determines how useful and, thereby, successful, the computer system is. So important is the interface that user will usually forgive the system if it is unable to provide all the information that the user needs. Their likely reaction would be to provide suggestions to improve the system.

Perception becomes reality in this instance. User perception determines whether they will accept the system and use it. Usage is one metric to judge how successful an information system is.

Users perform their tasks through the interface. Take the following example. The user has been instructed to:
  1. Search for data – “locate all credit sales last month”
  2. Classify the data – “classify these sales by store location”
  3. Organize it – “arrange each sale transaction by date, starting with the most recent to the oldest”
  4. Process it – “compute the total credit sale per store last month”
  5. Output it – “print out the results but only show the summary totals”
Accomplishing each task requires a series of keystrokes or mouse clicks. For example, to locate all credit sales last month, the user must be able to instruct the system to limit the search to credit sales only that occurred last month only. Depending upon the interface, the user might need to click on a button that specifies credit sales and also enter the dates manually in two fields that define a range of dates. Can you see how the interface design can make a significant difference in the user experience?

It takes forethought to design a good interface. Even then, especially during the first few versions, designers inevitably have to return and tweak the design. This will happen repeatedly. Interface design, therefore, is an iterative process.

Interface design assumes greater importance in a larger and more complex system. Good examples of a well-designed interface in a complex system are most of the user screens in an SAP R/3 system.

SAP R/3 is currently the most popular enterprise information system in the world. It has a modular design. Each module is an application. Modules might consist of a vertical application specific to an industry—the retail sector, for instance. Or, they may consist of horizontal applications that process a function—financial accounting, for example. All businesses—regardless of industry—require financial accounting.

A major factor behind the software’s acceptance (and, therefore, success) is its well-designed application windows (called “sessions” in SAP lingo). For such a complex system, I marvel at its windows. Practically all of its windows are consistently and logically defined. Most tend to be used intuitively. I have heard that in some cases, even someone new to operating a computer has been able to understand most SAP windows within several weeks.

The human-machine interface has evolved into a science. IBM, for example, has a Redbook (their term for a book compilation of technical information). Clicking here will bring up an IBM webpage that discusses the subject of the human-machine interface. Although it applies to web-user interfaces, the general principles remain the same. This Redbook states those principles succinctly:

  1. Is it just ease of use?
  2. What about user efficiency?
  3. Does the User Interface (UI) look like something that would be enjoyable to use?
You can judge the quality of a UI with a handful of factors:
  1. Ease of learning and memorability
  2. Efficiency of use
  3. Error frequency, severity, and recovery
  4. Subjective satisfaction
Now look at an ideal UI. It would:
  1. Be easy to learn
  2. Have a high maximum efficiency of use
  3. Have low error frequency
  4. Deliver subjective satisfaction to the user
I hope this helped you understand the importance of a software component that is frequently given cursory attention (although I notice it is changing for the better, i.e., developers are paying more attention to designing user-friendly interfaces). The interface can determine whether an information system is perceived to be successful or not.

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