Within the database, a number of important general and specific data conventions apply, depending on the type of variable in question, as follows:
All series are expressed in units, with the exception of index numbers, which typically have a base year value of 100.
All current and constant price value concepts are expressed in national currencies, with the exception of international trade series which, unless otherwise stated, are expressed in US dollars.
All quarterly data are seasonally adjusted and expressed at annual rates (i.e. rescaled by a factor of 4), and for all series in levels, annual data are calculated as the average of quarterly data.
All annual stock data refer to their end year values.
The annual values of ratio variables are calculated as the ratio of corresponding annual concepts, and therefore do not equal the average of the corresponding quarterly ratios. In particular this applies to annual price deflator series which are calculated as the ratio of annual current and constant price levels and therefore do not equal to the average of the corresponding quarterly deflator series. This contrasts with data for annual price indices, for example for consumer or retail prices, which are calculated as the average of the corresponding quarterly series.
All interest rates are expressed in per annum percentage terms and annual rates are calculated as the average of the quarterly rates. All bilateral exchange rates are expressed in terms of domestic currency units per US dollar, with annual values the average of individual quarterly rates.
Labour market statistics are expressed in terms of numbers of persons and corresponding annual figures are equal to the average of their quarterly values.