Interface design in computer-based language testing

There is no published material in the language testing literature on the process of, or good practice in, developing an interface for a computer-based language test. Nor do test development bodies make publicly available any information on how the interface for their computer-based language tests was developed. This article describes a three phase process model for interface design drawing on practices developed in the software industry, adapting them for computer-based language tests (CBTs). It describes good practice in initial design, emphasizes the importance of usability testing, and argues that only through following a principled approach to interface design can the threat of interface-related construct-irrelevant variance in test scores be avoided. The article also charts concurrent test development activities that take place during each phase of the design process. The model may be used in CBT project management, and it is argued that the publication of good interface design processes contributes to the mix of validity evidence presented to support the use of a CBT.