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Usability Evaluation and Prototype Fidelity: Users
and Usability Professionals, Catani, M.B. and Biers, D.W., Proceedings
of the Human Factors and Ergonomics Society 42nd Annual Meeting, 1331-1336,
(1998).
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One question that continues to be asked is how high does the fidelity
level of a prototype need to be in order for the prototype to be useful
in usability testing?
A study by Catani and Biers investigated the effect of prototype fidelity
on the information obtained from a performance test. They had three levels
of prototypes:
- Paper – low fidelity
- Screen shots – medium fidelity
- Interactive Visual Basic – high fidelity
Thirty university students performed four typical library search tasks
using one of the three prototypes. A total of 99 usability problems were
uncovered. The mean number of total problems encountered was:
- Low fidelity – 24.8
- Medium fidelity – 29.4
- High fidelity – 28.0
There were no significant differences in the number and severity of problems
identified, and there was a high degree of commonality in the specific
problems uncovered by users using the three prototypes.
These results seem to support the contention that one can extract as
much information from a usability test using low-fidelity (paper) prototypes
as from one using higher fidelity prototypes.
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Adding Interactivity to Paper Prototypes,
Uceta, F.A. Dixon, M.A. and Resnick, M.L., Proceedings of the Human Factors
and Ergonomics Society 42nd Annual Meeting, 506-511, (1998)
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Another study reported by Uceta, Dixon and Resnick had 10 participants
use either a paper-based prototype or a computer- based prototype. Each
participant used the prototypes to order various food and beverage items.
Both interfaces were exactly the same except for the medium of presentation,
and both prototypes contained the same number of usability problems.
Both approaches enabled users to find most of the usability problems.
The paper prototype group and the computer-based prototype group were
statistically comparable. However, testing with paper prototypes took
about 30% longer than with computer-based prototypes.
Once again, indepently from the previous study, no reliable differences
were found between the prototyping methods for finding usability problems.
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