Previous studies have indicated that when interfaces are designed consistently
with regards to structure and physical attributes, higher performance and lower
error rates are achieved than when interfaces are designed inconsistently. The
objective of this study is to develop a methodology to measure all aspects of
computer interface consistency and assess the impact of linguistic inconsistency
of interface design on user performance. The following nine factors which
contribute to consistency have been identified: Text Structure, General Text
Features, Text Content, Information Representation, Lexical Categories, Meaning,
User Knowledge, Physical Attributes, and Communicational Attributes. A
reliable and valid tool consisting of 94 questions has been developed to measure
consistency coprehensively. The instrument can be utilized both as an evaluation
and design tool for Web-based interfaces. The 9-factor, 94-item questionnaire
can be used to evaluate consistency of interfaces. Based on the data obtained
from 20 tasks, 25 guidelines have been established which can be utilized to
design consistent interfaces.