Statistics Explained, now in its fully revised Fourth Edition, is for students and researchers who wish to understand the statistical analyses used to analyse quantitative (numerical) research data in a wide range of academic disciplines, in particular, the behavioural, human and social sciences. This book explains, in a clear and informative manner, the logic of statistical analysis, in particular the null hypothesis significance testing (NHST) method. Using this method, a range of statistical tests have been devised for different types of data. Each of these tests is explained in the book by adopting a step-by-step ("walkthrough") approach with a specific illustrative example. Crucially, these explanations do not require the reader to have an advanced knowledge of mathematics or statistics, but only assumes the basic mathematics which most readers will have learnt at high school. The book also examines the criticisms of NHST and introduces the reader to Bayesian statistics. As a result the reader will be able to critically evaluate the outcomes of statistical analysis both of their own work and that of others. Statistics Explains will be of great interest to students and researchers in the behavioural, human and social sciences in understanding both the outcomes of their own research and also the research reports in the academic journals.