document: We have developed a systematic, quantified understanding of a specific problem: the design of mobile-friendly unique identifiers. But our results also apply to the design of other text-based services. There has been a trend toward bespoke and adaptive keyboards (e.g., Dunlop and Levine, 2012; Karrenbauer and Oulasvirta, 2014; Leiva et al., 2015; Wiseman et al., 2013). More often than not, though, input devices are a fixed constraint in the design of a service. Most users are typing on the keyboard that came with their phone. Those keyboards have advantages, limitations and quirks. The mode-switching that most touchscreen keyboards require to reach numbers and capital letters is at the root of design improvements we propose in this paper. When designing services, it is vital to be aware of the fixed constraints of a system and to then focus on the aspects of a service's design that can be controlled. Making changes to input data in this way is a cheap, quick and easy way to improve user experience.
extractive_keyphrases: bespoke and adaptive keyboards designing services design of a service input devices
abstractive_keyphrases: design of mobile-friendly unique identifiers design of other text-based services mode-switching