This text is aimed at students in medicine, biology, and the social sciences, as well as those planning to specialise in applied statistics. It covers the basics of the design and analysis of surveys and experiments and provides an understanding of the basic principles of modelling and inference. Practical advice is provided on how to design a study, collect data, record observations accurately, detect errors, construct appropriate models, and interpret the results. The text contains many illustrative examples and exercises relating statistical principles to research. A companion website is available with links to data sets, R codes, and to an instructor's manual with teaching hints and solutions.