A system for measuring an ability of a subject. The system includes a set of tasks that require the subject to provide one or more spoken responses. A speech recognition system, which is coupled to receive the spoken responses, provides an estimate of the spoken responses. The estimate may be an estimate of the linguistic content and/or other characteristics of the response. The speech recognition system has an associated operating characteristic relating to its ability to recognize and estimate the content of responses and elements of responses. A scoring device converts the response estimate into one or more item scores. A computation device provides a subject score using a scoring computation model that depends upon the expected item-dependent operating characteristics of the speech recognition system.