Many new assistive input systems developed to meet the needs of users with functional impairments fail to make it out of the research laboratory and into regular use by the intended users. This paper examines some of the reasons for this and focuses particular on whether the developers of such systems are focusing on the correct metrics for evaluating the functional attributes of the new input technologies. In particular, the paper focuses on the issue of benchmarking new assistive input systems against a baseline measure of interaction rate that takes allowance of factors such as input success/recognition rate, error rate, correction effort and input time. By addressing each of these measures, a more complete understanding of whether an input system is functionally acceptable can be obtained
