Metrics for text entry research: an evaluation of MSD and KSPC, and a new unified error metric

We describe and identify shortcomings in two statistics recently introduced to measure accuracy in text entry evaluations: the minimum string distance (MSD) error rate and keystrokes per character (KSPC). To overcome the weaknesses, a new framework for error analysis is developed and demonstrated. It combines the analysis of the presented text, input stream (keystrokes), and transcribed text. New statistics include a unified total error rate, combining two constituent error rates: the corrected error rate (errors committed but corrected) and the not corrected error rate (errors left in the transcribed text). The framework includes other measures including error correction efficiency, participant conscientiousness, utilised bandwidth, and wasted bandwidth. A text entry study demonstrating the new methodology is described.

• Type: Conference
• Year: 2003
• Where: CHI
• Authors: R. William Soukoreff, I. Scott MacKenzie
• Keywords: CHI 2003, Corrected Error Rate, Error Correction Efficiency, Human Computer Interaction, Total Error Rate