Basic Biostatistics for Geneticists and Epidemiologists: A Practical Approach by Robert C. Elston and William D. Johnson.

Anyone who attempts to read genetics or epidemiology research literature needs to understand the essentials of biostatistics. This book, a revised new edition of the successful Essentials of Biostatistics has been written to provide such an understanding to those who have little or no statistical background and who need to keep abreast of new findings in this fast moving field.