Cohort Studies.

Editor's note: This is the seventh article in a series on clinical research by nurses. The series is designed to give nurses the knowledge and skills they need to participate in research, step by step. Each column will present the concepts that underpin evidence-based practice-from research design to data interpretation. The articles will be accompanied by a podcast offering more insight and context from the authors. To see all the articles in the series, go to http://links.lww.com/AJN/A204.