I wrote this book to provide research workers in the biological, health and social sciences with the background that they need in order to collect and analyse data in an intelligent and critical manner. The last thing that I wanted to do was to write yet another text for a first statistics course for undergraduates, since there are many excellent texts already available for that purpose. Instead, I wanted to produce the type of book that will be of value to people who have already mastered the material that is usually presented in courses of that type, and who are ready and willing to know more about the aspects of statistics that are likely to be most useful to the quantitative researcher.

Of course, it is a matter of opinion as to what aspects of statistics are likely to be useful to researchers, and these will not be the same for everyone. However, it is my belief that many books on statistics that are meant for non-statisticians tend to place too much emphasis on mechanical calculations at the expense of emphasizing the important assumptions, the problems that can so easily occur, and the practical application of methods. For example, there are many books that teach how to do a t-test to see if there is any evidence that two sample means are significantly different.