Imagine you live in a world where everyone is the same; they are the same height, wear the same clothes, they all have the same taste in music and they all have the same needs and requirements when it comes to using mobile services and applications. If nothing varies between people then all that you need to know about people's attitude and performance when using mobile services and applications could be gathered from just one person. Just imagine how easy it would be todevelop new applications if this was the case. Some people might say, rather harshly, that this is what happens already.

However, as you know, variability is an essential aspect of the world we live in and it has an impact in the area of human computer interaction. So far, this book has highlighted aspects of variability (see Chapter 2 on user characteristics and Chapter 6 which deals with social usability) that could have a significant effect on mobile application uptake and design impact.

The aim of statistics in all of this is to help us to try and make sense of this variability. This variability is something you may have taken for granted as you developed your questionnaires, interview questions and chose your performance measures for use in our mobile HCI research. However, once you have that data you have to think about what you are going to do with it.

The first step you have to think about when you have your...