Validity in clinical research: a review of basic concepts and definitions☆

Abstract

This is the first in a series of papers broadly titled ‘Research Without Tears’ that will discuss fundamental and sometimes controversial areas of research methods. In general, papers in this section aim to inform or update the readership of theoretical and practical issues for research in the clinical sciences. Some of the review papers will be conceptual in nature whilst others may address specific topics related to research design and data handling. It is hoped that this will facilitate the individuals and teams to complete and disseminate their research. Another important aim of these papers will be to try to demystify the chosen topics for those people whose role is not exclusively research orientated.The aim of this specific review paper is to address the concept of validity in clinical research. This article will be followed, firstly, by a review paper that will investigate the topic of reliability in clinical research, and then by an original research article that places the determination of validity and reliability within a specific clinical context. The current paper will initially define key components of validity with regard to the general aims of research and the research design. This will include definitions of internal, external and ecological validity. Threats to internal and external validity will be discussed, as will remedies to these treats through the application of appropriate sampling and design. This paper will then investigate the narrower concept of the validity of the measuring tool or process. A brief definition will be followed by a discussion of the processes by which validity may be determined. Future papers will address other issues of relevance to the readership. The Editorial Board welcomes any specific ideas and/or submissions.