This edition covers ethics of animal research up to date, primarily by incorporating the thoughtful treatment of the issue by Hal Herzog in his recent text about human–animal interaction. It closes with a discussion of how to review the literature with a new section that includes specific tips on how to organize and write a literature review. This issue also includes a discussion of effect size, power, and meta–analysis, especially by showing the manner in which they are interrelated and significantly increases coverage of the methods used and the issues involved with conducting online research.