This paper presents the analytic hierarchy process (AHP) as a methodology for developing ratio scales from paired comparison data. The AHP offers several advantages over traditional psychophysical approaches for generating measurement scales. One advantage is its ability to readily quantify consistency in human judgments. Another is the ability of the AHP to provide useful empirical results in the event of a small sample of subjects and when the likelihood of obtaining meaningful statistical results may be restricted. Finally, the methodology requires no statistical assumptions regarding the distribution of human judgments. This paper demonstrates that the AHP can be applied to types of subjective data frequently acquired during human factors experimentation. In an empirical scenario, subjects performed paired comparison judgments on a set of five computer interfaces designed for an automated part recognition system. The objective was to rank these interfaces on the basis of users' perceptions regarding two interface characteristics: usability and learnability. Results of the analysis provide ratio scales for evaluating both interface usability and learnability.
User learning is of critical importance in evaluating interface usability (and in turn interface quality). The focus of this research in on interface learnability, where a stochastic model represents the learning process required for successful completion of human-computer interaction tasks. The parameter used to quantify learning is a learning rate. Of interest here is the validation of learning rate as a measure of interface quality. Learning rate was validated against two traditional measures of interface quality: task completion time, and error frequency. SuperCard, a Macintosh project utility, provided an empirical learning environment in which 32 participants learned 16 fundamental SuperCard tasks. Results of correlation analyses suggested the usefulness of learning rate as an indicator of interface quality. Our learning rate analysis identified four tasks presenting learning difficulties. (Analysis of task completion times identified two of these four tasks, and error frequency analysis identified one). Learning rate data captured all of the information available from the two traditional interface quality measures and identified two tasks disregarded by them. Incorporating learning rates in the interface evaluation process precludes time-intensive video tape analysis typically required by more traditional interface quality measures.
Operator role theory provides a conceptual framework for guiding function allocation during the system design process, and for analyzing the allocation of functions in an existing or proposed design. The present paper describes the basic tenets of operator role theory and presents a method for using those tenets in the processes of system analysis and design. Operator role theory holds that there are four generic operator roles that are possible in a given function. These four roles (Direct Performer, Manual Controller, Supervisory Controller, and Executive Controller) describe different relationships between humans and automation. The concepts and methods have been used and proven useful in system analysis and design for two helicopter cockpit systems, a computer control system interface, and a traffic management center.
Task Report (28 Sept. 92 to 4 Sept. 94)
Sponsoring Agency CodeContracting Officer's Technical Representative (COTR): Nazemeh Sobhi (HSR-30)
AbstractThis report documents an approach for designing an Advanced Traffic Management System (ATMS) from a human factors perspective. In designing the ATMS from a human factors perspective, a user-centered top-down system analysis was conducted. Methodologies employed in conducting this analysis, procedures for implementing such methodologies, and analysis results are reported.System objectives and performance requirements for the AIMS, as well as ATMS functionality, are derived. Human operator issues (assignment of operator roles to ATMS functions, specification of operator performance requirements, and identification of operator tasks) are also addressed. Results of the operator task analysis supported the preparation of a human factors specification for the ATMS.
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