A model of two-thumb chording on a phone keypad
Nirmal Patel, James Clawson, Thad E. Starner · 2009
When designing a text entry system for mobile phone keypads, a designer needs to overcome the ambiguity that arises from mapping the 26 letters of the roman alphabet to only 12 keys (0--9, *, #). In this paper, we present a novel two-thumb chording system for text entry on a standard 12-key mobile phone keypad and introduce a performance model based on Fitts' Law for an expert user. The model provides a behavioral description of the user and predicts a text entry rate of 55.02 wpm.