Scale development and validation are critical to much of the work in the health, social, and behavioral sciences. However, the constellation of techniques required for scale development and evaluation can be onerous, jargon-filled, unfamiliar, and resource-intensive. Further, it is often not a part of graduate training. Therefore, our goal was to concisely review the process of scale development in as straightforward a manner as possible, both to facilitate the development of new, valid, and reliable scales, and to help improve existing ones. To do this, we have created a primer for best practices for scale development in measuring complex phenomena. This is not a systematic review, but rather the amalgamation of technical literature and lessons learned from our experiences spent creating or adapting a number of scales over the past several decades. We identified three phases that span nine steps. In the first phase, items are generated and the validity of their content is assessed. In the second phase, the scale is constructed. Steps in scale construction include pre-testing the questions, administering the survey, reducing the number of items, and understanding how many factors the scale captures. In the third phase, scale evaluation, the number of dimensions is tested, reliability is tested, and validity is assessed. We have also added examples of best practices to each step. In sum, this primer will equip both scientists and practitioners to understand the ontology and methodology of scale development and validation, thereby facilitating the advancement of our understanding of a range of health, social, and behavioral outcomes.

Objective Progress towards equitable and sufficient water has primarily been measured by population-level data on water availability. However, higher-resolution measures of water accessibility, adequacy, reliability and safety (ie, water insecurity) are needed to understand how problems with water impact health and well-being. Therefore, we developed the Household Water InSecurity Experiences (HWISE) Scale to measure household water insecurity in an equivalent way across disparate cultural and ecological settings. Methods Cross-sectional surveys were implemented in 8127 households across 28 sites in 23 low-income and middle-income countries. Data collected included 34 items on water insecurity in the prior month; socio-demographics; water acquisition, use and storage; household food insecurity and perceived stress. We retained water insecurity items that were salient and applicable across all sites. We used classical test and item response theories to assess dimensionality, reliability and equivalence. Construct validity was assessed for both individual and pooled sites using random coefficient models. Findings Twelve items about experiences of household water insecurity were retained. Items showed unidimensionality in factor analyses and were reliable (Cronbach’s alpha 0.84 to 0.93). The average non-invariance rate was 0.03% (threshold <25%), indicating equivalence of measurement and meaning across sites. Predictive, convergent and discriminant validity were also established. Conclusions The HWISE Scale measures universal experiences of household water insecurity across low-income and middle-income countries. Its development ushers in the ability to quantify the prevalence, causes and consequences of household water insecurity, and can contribute an evidence base for clinical, public health and policy recommendations regarding water.

There is rapidly evolving literature on water insecurity in the general adult population, but the role of water insecurity during the vulnerable periods of pregnancy and postpartum, or in the context of HIV, has been largely overlooked. Therefore, we conducted an exploratory study, using Go Along interviews, photo-elicitation interviews, and pile sorts with 40 pregnant and postpartum Kenyan women living in an area of high HIV prevalence. We sought to (1) describe their lived experiences of water acquisition, prioritisation, and use and (2) explore the consequences of water insecurity. The results suggest that water insecurity is particularly acute in this period, and impacts women in far-reaching and unexpected ways. We propose a broader conceptualisation of water insecurity to include consideration of the consequences of water insecurity for maternal and infant psychosocial and physical health, nutrition, and economic well-being.

Introduction A wide range of water-related problems contribute to the global burden of disease. Despite the many plausible consequences for health and well-being, there is no validated tool to measure individual- or household-level water insecurity equivalently across varying cultural and ecological settings. Accordingly, we are developing the Household Water Insecurity Experiences (HWISE) Scale to measure household-level water insecurity in multiple contexts. Methods and analysis After domain specification and item development, items were assessed for both content and face validity. Retained items are being asked in surveys in 28 sites globally in which water-related problems have been reported (eg, shortages, excess water and issues with quality), with a target of at least 250 participants from each site. Scale development will draw on analytic methods from both classical test and item response theories and include item reduction and factor structure identification. Scale evaluation will entail assessments of reliability, and predictive, convergent, and discriminant validity, as well as the assessment of differentiation between known groups. Ethics and dissemination Study activities received necessary ethical approvals from institutional review bodies relevant to each site. We anticipate that the final HWISE Scale will be completed by late 2018 and made available through open-access publication. Associated findings will be disseminated to public health professionals, scientists, practitioners and policymakers through peer-reviewed journals, scientific presentations and meetings with various stakeholders. Measures to quantify household food insecurity have transformed policy, research and humanitarian aid efforts globally, and we expect that an analogous measure for household water insecurity will be similarly impactful.