An index number of the prices of goods of some given type. If only one good i is concerned, period 0 is the base period and period t the current period, where p_it is the price in period t, the price index is given by p_it /p_i0. This gives the index in ratio form: to obtain it in percentage form multiply by 100. If a class of goods i = 1, 2, …, N is concerned, the price index is a weighted average of the indices of their prices. The weights are the values of the goods purchased in some period. If q_it is the quantity of good i in period t, the base-weighted or Laspeyres price index is defined as p_B = (σ_i p_it q_i0)/(σ_i p_i0 q_i0 ) and the current-weighted or Paasche price index is defined as p_C = (σ_i p_it q_it )/(σ_i p_i0 q_it ). Again these are in ratio form: to obtain them in percentage form multiply by 100. Price indices can also be found for securities or wage rates.

• asset prices
• assets
• asset-stripping
• asset, wasting
• Assisted Area
• association
• assurance
• asymmetric information
• asymptote
• atomistic competition
• auction
• audit
• auditor
• autarky
• authorized capital
• autocorrelation
• automatic stabilizers
• automation
• autonomous consumption
• autonomous investment
• average
• average cost
• average cost curve, U-shaped
• average cost pricing
• average propensity to consume