ECA Price Watch Centre for Africa - Methodological notes
1. Definitions:
Consumer price index: The consumer price index (CPI) measures changes over time in the general level of prices of goods and services that a reference population acquires, uses or pays for consumption.
Inflation: The inflation indicates the movements of the level of prices and is measured as percentage variations of the consumer price index, from a reference point which can be the previous period, month, quarter or year.
2. Data sources:
The data published on this site are computed by UNECA by combining the data produced and released by its member countries, and data available in databases of international organisations (IMF, SADC, COMESA).
More specific details on country references can be found under the other resources page.
3. Aggregation methods:
The basic price data sourced from countries are consumer prices indices. These indices are rebased to year 2010 as common base period for all countries price series, allowing the easy comparison of trends and computation of aggregations for groups of countries and various periods of time.
Time aggregations: The Time aggregations refer to the move from monthly CPI and inflation figures to quarterly and annual CPI and inflation figures. For each geographical entity (country and group of countries), the quarterly and annual CPIS are derived as simple average of the monthly CPIs within the period. This is done on the rebased CPI series (2010=100).
The monthly, quarterly and annual inflations are then derived from the Monthly, quarterly and annual CPIs, as growth rates over the previous period (month, quarter, year) or over the same period of the past year (monthly and quarterly).
Geographic aggregations: For the various country groupings, the aggregations are done starting from the rebased monthly CPIs (2010=100). The aggregated monthly CPIs are obtained as weighted average of the CPIs of the countries composing the groupings; the weighting factor used is the 2010 GDP at current prices in international dollars ($PPP), i.e. corrected from differences in price levels among the countries.
For the country grouping the subsequent quarterly and annual CPIs and inflations rates are generated as per the time aggregation method described above.
Geographic aggregations have been computed for the African Regional Economic Communities: Arab Maghreb Union (AMU), Common Market for Eastern and Southern Africa (COMESA), Community of Sahel-Saharan States (CEN-SAD), East African Community (EAC), Economic Community of Central African States (ECCAS), Economic Community of West African States (ECOWAS), Inter-Governmental Authority for Development (IGAD), and Southern African Development Community (SADC).
Due to incomplete data series, the following countries have not been taken in consideration in the regional aggregations: Eritrea, Libya, Somalia, South Sudan.
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