  This study addresses the problem of generating an optimised keyboard layout
for single-finger typing on a smartphone. It offers Twitter users a
tweet-typing experience that requires less effort and time. Bodies of tweet
text for 85 popular Twitter users are used. While existing studies have
produced optimisations that may generally benefit a variety of users, this
study is unique in the sense that a bespoke optimised keyboard layout is
generated for each Twitter user based on their own tweets, thereby uniquely
benefiting them more than other users. The optimisation process is based on
moving only six letter keys from their positions on the QWERTY keyboard, and
therefore strikes an effective balance between the typing efficiency
improvements offered by an optimised keyboard layout and the effort required to
learn to use it. It is shown that a Twitter user will enjoy a reduction in
typing effort of at least 13.4%. The typical user will benefit from a 15.8%
reduction, while the highest typing effort reduction is nearly 25%. The method
presented in this study could therefore be used in practical ways to offer any
Twitter user a uniquely-improved tweeting experience.
