Hybrid evaluation method for Korean Character input system in mobile phones

In this study, hybrid evaluation incorporating the Hick-Hyman law was proposed to predict input performance of a Korean input system applied to the number pads of mobile phones. The hybrid model, calculated based on the Hick-Hyman law, is a combination of reaction time (RT) and movement time (MT) model, which is a better model for predicting user performance than the conventional models that were used to assess Korean input system evaluation such as the Fitts' and the KLM-GOMS models. Along with Fitts' model (of visual-controlled movements), the simple movement time (SMT) and ballistic movement time (BMT) models (of ballistic behavior movement) were also evaluated to measure MT. Results showed that ballistic behavior movement was more compatible than visual-controlled movement. In ballistic behavior movement, a thumb-movement distance of <21 mm was closer to the SMT than the BMT model. These results indicate that when applying hybrid model movement, the displacement, and the target size properties of mobile phone users is required in the engineering of a predictive model. Thus, the suggested hybrid evaluation is meaningful in that it can evaluate users' input behaviors very appropriately in the case of hand-held input devices. Relevance to industry: A hybrid model based on Hick-Hyman law was determined to be effective to evaluate text input systems for the hand-held input device. This effective hybrid model can provide more accurate prediction time for text input behaviors to its designers for efficient system design. To its usability engineers, this hybrid model for more accurate prediction time can also provide an effective quantitative tool for usability evaluations for hand-held input device manufacturing industries because this model can save efforts as well as time for usability testing. (C) 2012 Elsevier B.V. All rights reserved.