The Producer Price Index (PPI) is designed to monitor changes in prices of items at the first important commercial transactions. The PPI shows the same general pattern of inflation as does Consumer price index, but is more volatile. This is because it is weighted more heavily towards goods that are traded in highly competitive markets and somewhat less sensitive to changes in the cost of labour. In principle, the PPI should include service industries, but in practice it is limited to the domestic agricultural and industrial sector. The prices should be farm-gate prices for the agricultural sector and ex-factory prices for the industrial sector. The PPI is worth watching as a leading indicator of inflation at the consumer level. Price changes at the wholesale level take time to work their way through to the retail store. Data before January 1995 is recalculated on the old base 1991=100