What is Brand Development Index?

Legal Definition
Brand Development Index or BDI quantifies how well a brand performs within a market, compared with its average performance among all markets. That is, it measures the relative sales strength of a brand within a specific market (e.g., the Pepsi brand among 10–50 year old's).
-- Wikipedia
Legal Definition
Brand Development Index or (BDI) measures the relative sales strength of a brand within a specific market (e.g. Pepsi brand in 10 - 50 year olds). It is a measure of the relative sales strength of a given brand in a specific market area.