Evelyn Davis & Steven Davis 
Data Analysis with SPSS Software [PDF ebook] 
Using the t-Test

Building on the tools and techniques found in the popular statistics computer program, SPSS, this series of six books introduces the reader to the concepts of data, their categorical types, how data can be organized and manipulated, and how they can be put to practical use in solving everyday problems in science, business and technology. This third of 6 books introduces the concept of inferential statistics, , which is particularly useful when trying to measure significance in small data sets. The book goes on to explain the t-Distribution, and working out t-Tests for both independent and dependent groups of data. Worked out exercises help to clarify the principles explained in the book.