Introduction: Statistics, Non-mathematical Methods and How to Use this Book.- Probability, Samples, Buckets and Balls.- Summing Things Up: Graphs, Averages, Standard Deviations, Correlations and so on.- Why Use Statistics? Pros, Cons and Alternatives.- Calculating Probabilities: Mental Ball Crunching and Computer Games.- Possible Worlds and Actual Worlds: How Can We Decide What's True?.- How Big is the Error? Confidence Intervals.- Checking if Anything is Going On: Tests of Null Hypotheses.- Predicting the Unpredictable, or Explaining the Inexplicable: Regression Models.- How to Do It and What Does It Mean? The Design and Interpretation of Investigations.- Appendix A: Using Spreadsheets (Excel) for Statistics.- Appendix B: A Brief Guide to the Statistical Package, SPSS.- Appendix C: Data and Program Files for Downloading.- Appendix D: Comments on Some of the Exercises.- Notes.- References.- Index.