Scales and instruments play an important role in health research and practice. It is important that studies that report on their psychometric properties do so in a way such that readers can understand what was done and what was found. This paper is a guide to writing articles about the development and assessment of these tools. It covers what should be in the abstract and how key words should be chosen. The article then discusses what should be in the main parts of the paper: the introduction, methods, results and discussion. In each of these parts, it suggests the statistical tests that should be used and how to report them. The emphasis throughout the paper is that reliability and validity are not fixed properties of a scale, but depend on an interaction among it, the population being evaluated and the circumstances under which the instrument is administered.Keywords: diagnostic tests, instrument development, nursing assessment, psychometric testing, research methods, statistics Classifications, scales and standardized assessment instruments form an integral part in nursing research and practice. On the ward or in a clinic, they are used to measure phenomena such as pain (Stinson et al. 2008), quality of life (Dolan 1997), dyspnoea (Stenton 2008) and a host of other subjective states that would be difficult to assess in any other way. They can be used to help in diagnosing some disorder (Stice et al. 2000), assessing the degree to which the patients' problems are interfering with their lives (Devins et al. 2001), or tracking how much they improve or do not improve after some intervention (Kells et al. 2013). Additionally, a wide range of risk assessment instruments are used to quantify degrees of susceptibilities of complex phenomena like pressure ulcers (Kottner & Balzer 2010) or the risk of falling (Kehinde 2009). In research settings, scales and instruments are often the primary outcome measure and the success or failure of an intervention is often determined on the basis of differences between groups on some scale (Sawatzky et al. 2013). Those who develop scales have more than risen to the challenge. The most recent edition of the Mental Measurements Yearbook (www.ebscohost.com) lists over 3,000 commercially available scales and this is dwarfed by the number of instruments that have not been published, which is at least four times larger (Goldman & Mitchell 2008). The good news is that it is possible to find an existing scale to measure almost any outcome of interest. The bad news is that it is difficult to evaluate many of these measures because their psychometric properties -that is, their reliability and validityare not adequately reported.Over the years, several guidelines have been written to assist authors who are reporting on the development of new These three standards are essential readings for anyone who wants to publish a paper reporting on the development or investigation of scales or instruments. However, it should be noted that there are situations, especially in health and nursing re...