In defining human factors/ergonomics requirements, user questionnaire data are often employed. These data can be difficult to interpret and may lead engineers to discard data post hoc because an explanation is not apparent. Such a process leads to erroneous conclusions and poor design. A structured approach to data interpretation is required to prevent such errors including consideration of (a) question comprehension, (b) bias across the user sample, (c) variability in user cognitive models, (d) user differences in intended method of, or strategy for, interfacing with a design, and (e) user attachment to an old design.. This approach should provide the human factors/ergonomics engineer with a clearer insight into the perceptual-cognitive processes which form the basis for responses and aid in the ability to define requirements for the user interface.