Definition: Diffusion index
OECD - Business tendency surveys
A diffusion index provides a summary of answers to multiple-choice questions in business tendency surveys. It is defined as the fraction of favourable answers plus half of the fraction of no change answers. Diffusion indices are alternatives to "Balances" as a way of summarising answers to multiple-choice questions.
Organization for Economic Cooperation and Development (OECD), "Business Tendency Surveys - A Handbook", OECD, Paris, 2003