A few years ago, I was working with a client who was interested in a mobile application for the field personnel. There was a focus on moving to a Palm Pilot. During the discussions, even the field personnel were driven towards the Palm Pilot. In a meeting, I asked everyone to hold up their hands. As everyone's eyes scanned the room, I pointed out the relative size of everyone's hands. The forest of engineer's fingers and thumbs were very thick. The field personnel were required to maintain text narratives of their observations. The reality of visualizing these stocky field personnel trying to type on thumb keypads in the field was stark. We recommended toughbook tablets enabled with CDMA wireless connectivity to which the client agreed.
Throughout your product life cycle keep a visual image of who your user is. Are they using laptops or desktops? What is their physical data entry environment? Do they love using a mouse or hate it? You may not be able to (or desire to) tailor the application that closely to the user. However, the nuances of the Engineer's thumb can be the difference between success or failure.
