Introduction

Before the spread of personal computers, researchers had to do most things by hand (by which I mean with a calculator), and so most statistics books were full of equations and their derivations, with many pages of the necessary statistical tables. Analysing anything other than small samples could be time-consuming and error prone. You also needed to be reasonably good at maths. Of course, for the statistics specialist there is still a need for books that deal with statistical theory, and the often complex mathematics which underlies the subject.

However, now that there are computers in most offices and homes, and many professionals have some access to a computer statistics programme, there is room for books which focus more on an understanding of the principal ideas which underlie the statistical procedures, on knowing which approach is the most appropriate, and under what circumstances, and on the interpretation of the outputs from a statistics program.

I have thus tried to keep the technical stuff to a minimum. There are a few equations here and there (most in the last few chapters), but those I have provided are mainly for the purposes of doing some of the exercises. I have also assumed that readers will have a nodding acquaintance of either SPSS or Minitab. Short courses in these programs are now widely available to most clinical staff. I also provide a few examples of outputs from SPSS and Minitab, for the commonest applications, which I hope will help you make sense of any results you get. Both SPSS and Minitab have excellent Help facilities, which should answer most of the difficulties you may have.

Remember this is an introductory book. If you want to explore any of the methods I describe in more detail, you can always turn to one of the more comprehensive medical statistics books, such as Altman (1991), or Bland (1995).

I

Some Fundamental Stuff