A number showing the size of some variable, relative to a given base. The base may be assigned any value, but is normally chosen to be either 1 or 100. For a time series, the base may be the value at a given date; for cross-section data, it may be some chosen instance, or the mean of the items covered. Where an index number describes a constructed variable, such as ‘the price level’, which is an average of prices, or gross domestic product (GDP), which is an aggregate of many different sectors, it is a weighted average of the index numbers for the various components. A base-weighted index or Laspeyres index uses as weights the relative sizes of the different items at the base period; a current-weighted index or Paasche index uses as weights the relative sizes of the component items during the current period.

• correlation
• correlation of returns
• corruption
• corset, the
• cosine
• cost
• cost accounting
• cost-benefit analysis
• cost centre
• cost curve
• cost-effectiveness
• cost function
• cost inflation
• cost, insurance, and freight
• cost minimization
• cost of capital
• cost of living index
• cost of protection
• cost-plus pricing
• cost-push inflation
• costs
• cost schedule
• council
• Council for Mutual Economic Assistance
• council housing