Analyzing performance with computer access technology using unconstrained text entry protocol.

Recent work in human-computer interaction has demonstrated the use of unconstrained text entry protocols, which provide a more natural environment for research participants. We demonstrate the application of this approach to the analysis of word completion. Eleven participants (five nondisabled and six with disabilities) were recruited and asked to transcribe sentences using an on-screen keyboard both with and without word completion while time-stamped keystroke data were collected. The subsequent analysis demonstrates how the entire input stream (including erroneous keystrokes and the keystrokes used to correct errors) can be included in evaluation of performance with a text entry device or keystroke reduction method. Three new measures of keystroke savings are introduced, and the application of these measures is demonstrated.