Measuring errors in text entry tasks

We propose a new technique based on the Levenshtein minimum string distance statistic for measuring error rates in text entry research. The technique obviates the need to artificially constrain subjects to maintain synchronization with the presented text, thus affording a more natural interaction style in the evaluation. Methodological implications are discussed, including the additional need to use keystrokes per characters (KSPC) as a dependent measure to capture the overhead in correcting errors.