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A study was conducted to obtain performance data for entering text on a mobile phone in order to compare it to performance predictions based on two different mathematical models. Speed data was obtained for two text input methods, T9 Text Input and Multi-tap. While the direction of the results was the same for both the performance data and both model predicitons (with predictive text entry being faster than Multi-tap text entry), the results for all three differed in magnitude. Suggestions for this discrepancy are provided. In addition, in order to help shape future models, additional results are presented for both input methods to show how both accuracy and speed performance varies based on user experience and text subject matter.
James et al. (Thu,) studied this question.