This short book is intended to be a practical guide, providing sets of rules that will help you to analyse the data you collect in your regular experimental sessions in the laboratory. Even more important, explanations and examples are provided to help you understand the ideas behind the formulae. Emphasis is also placed on thinking about the answers that you obtain, and on helping you get a feeling for whether they are sensible.

In contrast, this does not set out to be a text on statistics, and certainly not to be a complete course on the subject. Also, no attempt is made to provide rigorous mathematical proofs of many of the required formulae. These are important, and if required can be consulted in any standard textbook on the subject.

I believe that it will be necessary to read this material more than once. You really need to have understood the ideas involved before you do your first practical; but on the other hand, it would be much easier to absorb the material after you have actually done a couple of experiments and grappled with problems of trying to do the analysis yourself. Thus it is a good idea to read the book quickly, so that you at least discover what topics are covered and where to find them again when you need them. At this stage, you need not worry if not everything is entirely comprehensible.