Updates to World Development Indicators: Purchasing Power Parities and Maternal Mortality Ratios

Two major updates to time series published in World Development Indicators (WDI) mean that the WDI database will be updated “out of timetable” on May 6; the regular schedule is April, July, September and December. These updates will affect all on-line products which draw on the WDI database, including the website data.worldbank.org, on-line tabulations, mobile applications, and the on-line WDI database itself. Please note that these updates will not be included in printed publications for which the data cut-off date was prior to May 6, such as the 2014 edition of World Development Indicators and the Little Data Book.
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Purchasing Power Parities
The first dataset is a new set of Purchasing Power Parities for 2011, released by the International Comparison Program (ICP) on April 30. The previous update to this series occurred in 2008, when the ICP released PPP data for the year 2005. There are several series and derived series that will change with the updated estimates:

PPPs allow comparison of real levels of expenditure between countries, just as conventional price indexes allow comparison of real values over time, and are calculated by simultaneously comparing the prices of similar goods and services among a large number of countries. PPPs are published by the ICP only for a single benchmark year, although the OECD and Eurostat publish estimates for 47 countries on an annual basis.

The WDI includes these annual estimates from OECD and Eurostat, but for other countries annual estimates are derived from the benchmark year through a simple extrapolation method using appropriate deflators. For example, for the series PA.NUS.PPP (PPP conversion factor, GDP), the method uses the relative rate of inflation observed in the implicit GDP deflator of the country of interest compared with the US GDP deflator - the implicit GDP deflator being the ratio of the current and constant price GDP series. A comprehensive treatment of the extrapolation method - and its limitations – is provided by the ICP in chapter 18 of the ICP Book “Measuring the Real Size of the World Economy”. As noted there, the longer the time period between the estimate and the benchmark, the greater the risk of inaccuracy.

On May 6 new annual PPP series and related indicators for 1990 through 2012 will be included in the WDI, for those countries and economies where the necessary series of appropriate deflators are available. These series will be derived by estimating PPPs by extrapolating backward and forwards from the new 2011 benchmark results. However, users should be aware of the limitations of this approach. Please note that 2013 estimates will be included in the database on July 1, 2014, as per the regular timetable.

Maternal Mortality Ratios
The second dataset relates to updates to global estimates of maternal mortality, which have been calculated for the benchmark years of 1990, 1995, 2000, 2005, 2010 and 2013, and are revised periodically when new data or improved methods are introduced. The estimates are compiled by the Maternal Mortality Estimation Inter-Agency Group, which includes the World Health Organization, the United Nations Children’s Fund, the United Nations Population Fund, the United Nations Population Division, and the World Bank Group, in collaboration with an academic team from the National University of Singapore and the University of California, Berkeley.

The revised estimates for 1990-2013 will be published on May 6, using new data from 77 studies and 2 additional countries - Kiribati and South Sudan, and using improved methods of estimating births and female deaths, in close consultation with countries. Four series in World Development Indicators will be affected by this update:

The new maternal mortality estimates will also be available in the HealthStats website.

As always, your comments and suggestions are welcome, either through the on-line help desk system, or via email at data@worldbank.org.