Reflections on the value and impact of library and information services: Part 2: impact assessment

Purpose– The purpose of this paper is to critically review methods of impact assessment and economic analyses.Design/methodology/approach– Reviews the literature on impact assessment, and examines some case studies of impact assessment in health libraries. Relates satisfaction and dissatisfaction assessment to impact assessment. Identifies recent impact assessment approaches in public and academic libraries, and explores different uses of terminology for impact and outcome. Reviews literature on economic analysis of value, including cost analyses, cost-effectiveness analysis and return on investment (ROI) studies.Findings– Terms for library assessment (outcome, output, impact, value and benefit) vary among different sectors. Impact evaluation should examine initial assumptions of value carefully, and examine possible gaps in the line of argument linking inputs of library services to presumed impacts (positive and negative). More attention to sampling and response rates is required, to avoid problems such as the “warm glow” effect. Qualitative and quantitative evidence should be carefully integrated to tell the impact story. Economic impact can be estimated, but methodology depends on the service aims and sector.Originality/value– Demonstrates that some of the requirements for traditional impact assessment also affect economic analyses and ROI studie