Different measures for evaluation
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Measures of Evaluating Human-Computer Interfaces
Utility
The fundamental goals of HCI is "to develop or improve the safety, utility, effectiveness, efficiency, and usability of systems that include computers” (Interacting with Computers, 1989, p. 3). Utility means that the product can reach a certain goal or to perform a certain task. In another word, utility means the functionality of the system.
For any interface, the basic requirement is to achieve a certain goal properly as request. Thus, when utility of an interface is evaluated, three aspects are mostly concerned:
1)what is the purpose of the system and items in the interface;
2) how the main system performs for the certain task;
3) how the accessory functions perform.
For the first question, manufacturer and user will focus on both the purpose of the system and the purpose of each item designed. The company and user may review the goal of the system. Widget(menu, button, etc.) is also evaluated for its purpose, and may be removed or added as demand.
For the question two, the performance of the whole system will be considered. Whether it will perform properly as request and designed will be judged. The HCI may be tested either in a simulation test environment by expert, or may be evaluated by real user.
Also other widgets in the interface should be considered. Some widgets may not related to the major task of the system but still very import (such as help or warning). These functions cannot be ignored in the utility evaluation.
Concerning the three questions above, GOMS, Expert reviews and User-based tesing(especially quantitative measures) are most common methods to evaluate utility of an interface. In addition, surveys can also evaluate the functionality of the HCI.
Utility is only the essential requirement of the HCI. Evaluation in other aspects are improtant as well.
Efficiency
Many technological product, neuclear reactor, control system, require the HCI to fuifill their technical complexity to a usable product. Technology alone may not win user acceptance and subsequent marketability. The User Experience, or how the user experiences the end product, is the key to acceptance.
For a given HCI, company and users usually more concern about the following questions:
1) How easy for new user to lean to operate the interface?
2) How much time and effort it takes an operator to finish a given mission without any supervision?
3) And more important, what is the improvement on the productivity by using the HCI?
If the user feels the HCI too hard to learn, or not easy to use, software will not to be accepted by the users no matter how well it is. Good User Interface Design can make a product easy to understand and use, which results in greater user acceptance.
In HCI, efficiency is measured as the resources expended by the user in relation to the accuracy and completeness of goals achieved. High efficiency is achieved when the user finish the mission with few resources in terms of time cost, leaning cost as well as maintain cost, etc.
There are several criteria that will be used to measure the efficiency of the Human computer interface. The criteria include the design, usability and performance of the HCI. The Data Envelopment Analysis (DEA) technique can be used to meansure the HCI efficiency.
There are design to improve the efficiency of the HCI
1)Consistent screen design
2)Menu not too long, not contains too many items
3)Enable Help function, which should contain the procedure for common issues
4)Animation and image could be used to simulated the realworld situation
5)Enable the error message in order to warn as well as offer useful suggestion
6)Design similar to other related software
7)provide online help and tutorial
Learning Ability
taken by C.G. Ban
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User Satisfaction
However the user satisfaction with a human-computer interface can be seen as a special case of the user satisfaction with the whole system, it is the most important part. No matter how good the system is, with discouraging, hostile or even wrong interface in eyes of the users, it will never be used effectively. Even according to the international standard on usability, ISO/DIS 9241-11(ISO, 1997) the three pillars of usability are efficiency, effectiveness and user satisfaction.
User satisfaction evaluation is always based on survey among the end users. It can be performed in form of interviews or questionaires. The group of questioned users should contain all the possible kinds of users (in all the possible senses), otherwise such evaluation will not be objective and future refinement can even make the interface worse. It is important that the group is motivated and willing to give the feedback.
Examples
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References
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