A Rapid Screening and Testing Protocol for Keyboard Layout Speed Comparison

We propose an efficient low-overhead methodology for screening key layouts for ultimate typing speed. It is fast and complementary to existing protocols in other ways. For equal overhead, it allows testing over a wider range of users. It is subject to potential biases, but they can be quantified and adjusted. It assumes an existing standard layout which is used as a comparator. It eliminates bias from differing familiarity and finger memory by appropriately mapping both layouts. We illustrate it with two mobile phone keypad layouts: Samsung's variant of the common ABC layout, and a new user-specific layout (PM). We repeat a comparison previously undertaken by a training-based method, which used ten participants, and estimated a 54\% speedup for PM (SD = 35\%). The new method used 116 participants and estimated a 19.5\% speedup (SD = 7.5\%). Differences in speedup estimates can be explained by the wide confidence interval of the training-based methods, differences in test corpuses, and the inherent conservatism of the new method. Effects of user characteristics could be meaningfully tested due to the larger test group. Gender had no detectable effect on any of the measures, but age and keypad experience were significantly related to ABC and PM performance. However, the relative speedup was unaffected by age or keypad experience: the method can remove comparison biases arising from differing experience levels.