Development of the item pool for the 'WHO-ageism scale': conceptualisation, item generation and content validity assessment.

objectivesageism harms individuals' health and wellbeing and can be costly to societies. Reliable and valid measures that can quantify ageism are critical for achieving accurate data on its global prevalence, determinants and impacts, and to evaluate the effectiveness of interventions to reduce it. Ageism scales exist; however, none have been demonstrated to validly measure ageism in a manner consistent with consensus definitions of the concept (i.e. as manifested in all of stereotypes, prejudices and discrimination), whilst also quantifying ageism against all groups, from a target and perpetrator perspective, and across diverse country settings. Our objective was to develop an item pool to meet this need.

methodswe completed the conceptualisation, item generation and content validity assessment phases of a new World Health Organisation (WHO) WHO-ageism item pool that aims to measure the multi-dimensional nature of ageism. These phases drew on a review of available evidence, an experts' workshop and structured content validity reviews conducted by experts in scale development and ageism drawn from every world region defined by WHO.

resultsour resulting item pool is designed to provide a multi-dimensional measure of ageism against all ages measured from both a perpetration and experienced perspective and that can produce valid and reliable scores within diverse country contexts and comparable scores across these contexts.

conclusionsour item pool is the first major step in providing a global and comprehensive measure of ageism. Future phases of research will refine the item pool and establish the statistical psychometric properties of the final tool.