ArticlesResearch Methodology for the Internet External Validity (Generalizability)LaCoursiere, Sheryl RN, PhDAuthor Information From the Center for Excellence in Chronic Illness Care, Yale University School of Nursing, New Haven, Conn. The author thanks Karyl Burns, RN, PhD, for her assistance with the preliminary manuscript, and Peggy Chinn, RN, PhD, FAAN, Henrietta Bernal, RN, PhD, Cheryl Beck, DNSc, CNM, FAAN, and Regina Cusson, RN, PhD, for their review and suggestions. Corresponding author: Sheryl LaCoursiere, RN, PhD, Center for Excellence in Chronic Illness Care, Yale University School of Nursing, 100 Church St S, PO Box 9740, New Haven, CT 06536 (e-mail: [email protected]). Advances in Nursing Science: October 2003 - Volume 26 - Issue 4 - p 257-273 Buy Abstract The burgeoning use of the Internet for nursing research calls for a need to examine characteristics of electronic populations, and how they can be conceptualized relative to their physically based counterparts. The 1963 work of Campbell and Stanley, now 40 years old, is revisited in relation to external validity, and its applicability to today's world of quantitative and qualitative research. Internal and external differences in Internet populations are outlined, and a new threat to external validity is proposed: the threat of Networked Effects, which is composed of 4 subfactors: Co-occurring Interferences to Testing, Self-selection Mechanisms, Electronic Group Environments, and Cultural Differences. These Internet threats must be well understood when formulating research methodology. © 2003 Lippincott Williams & Wilkins, Inc.