# Conversions and Formulas

#### Current price series in US Dollars

• Data in current prices in US Dollars are converted from data in current prices in national currency using annual period-average exchange rates.

#### Constant price series in US Dollars

• Data in constant prices in US Dollars are converted from data in constant prices in national currency using the annual period-average exchange rate of the base year for all years.

#### Per Capita GDP/GNI

• Per capita GDP/GNI is GDP/GNI in current prices in US Dollars divided by the population.

#### Weight of GDP

• The weight of GDP as percentage of total GDP for the region is derived from GDP in US Dollars for the base year, using the following formula: #### Weight of Components

• The weight of each component as percentage of total of that component for the region is derived from the values in US Dollars for the base year, using the following formula: for each component.

#### Rate of Growth of GDP

• The growth rate of GDP is derived on the basis of constant price series in national currency, using the following formula: where y denotes the year.

#### Rate of Growth of Components

• The growth rate of each component is derived on the basis of constant price series in national currency, using the following formula: where y denotes the year.

#### Average Rate of Growth

• The average growth rate for a period of n years is derived as the geometric mean of the annual growth rates for that period, using the following formula: #### Percentage Distribution (Share of GDP/Value Added)

• The share of each component of GDP/Value Added is derived on the basis of current price series in national currency, using the following formula: for each component and for each year.

#### Price Adjusted Rate of Exchange (PARE)

• PARE rates are calculated by applying GDP deflator changes in National Currency Unit (adjusted for USD price changes) to the year closest to the year in question with a realistic GDP per capita US Dollar figure. By default the alternative conversion rate is calculated backwards. The PARE rate is calculated as: where xy is the exchange rate (either IMF Market Exchange Rate, Official Exchange rate or UN Operational Rates) of year y, where year y is the year for which an alternate conversion rate is needed and year y+n is the year with the realistic GDP per capita US Dollar figure used for the calculation. is the change in the GDP deflator, and is the GDP deflator for a given year y.

Example: A country’s GDP per capita 1987 would be 14000 US dollar, while it was 960 in 1982 and 700 in 1992. Between 1984 and 1991 the country suffered from hyperinflation while MERs were not allowed to adjust adequately to market prices. Using 1992 as a base and applying the PARE rates backwards to 1983 results in a GDP per capita series with a more plausible value of 770 for 1987, the year in question.