PGE Frequently Asked Questions

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How to . . .

Wait, how can I download the data again?

First, click on this link. Scroll down past the description until you see a list of files. The dataset is a .zip file, the latest version will be listed first. Clicking on the big downward-pointing-arrow icon on the right side of this line will show a menu; choosing “ZIP Archive” will download the file.

I’m using an older version of Stata, and it won’t open the file. How can I use the PGE data?

Stata 13 introduced a new file format which older versions of Stata can’t open. Fortunately, there’s an easy fix: the use13 command. In the command window, first type ssc install use13 to install it. Then you can type use13 pge1_0.dta, clear (change the version number as necessary, ofc) to load the PGE data.

I imported the pge_summary.csv file, and the data for some countries seem to be greater than one, when the PGE supposedly ranges only from zero to one. How can I interpret these data?

The issue here is that the pge_summary.csv file is saved using RFC 4180 csv conventions, that is, with a dot marking the decimal and a comma separating values. If you are in a locale that observes different conventions—many countries use commas to indicate the decimal and semicolons to separate values—your software’s default settings may not read the data correctly. Be sure to specify the decimal marker and value delimiter appropriately when loading the file: all PGE values fall between zero and one.

How can I use the PGE data with Stata’s time-series operators?

To use Stata’s time-series operators (l. , f. , d. , etc.), you must first declare the time and panel variables using tsset, but the PGE is already mi set, so tsset won’t work. Run the following before merging the rest of your data (called my_data.dta in this example) into the SWIID:

How can I use the PGE data to make my own graphs?

The PGE download contains files pre-formatted for use with the tools for analyzing multiply-imputed data and other data measured with uncertainty in Stata (e.g., pge1_0.dta) or R (e.g., pge1_0.rda). This is meant to “set the default” in a way that encourages researchers to take into account the uncertainty in the PGE estimates. This uncertainty is considerable in many countries, and the tools available in both software packages can now handle pretty much any analysis one may desire (for details, read the documents R_pge.pdf and stata_pge.pdf in the PGE download). But this format does not lend itself to graphing. For this purpose, use the summary file (e.g., pge1_0_summary.csv), which presents the PGE estimates in mean-plus-standard-error summary format.

How can I merge my other data into the PGE using ISO or other country codes?

First, add whatever country codes are needed to the PGE data: there are routines for both Stata (kountry; type findit kountry in Stata’s command window to install) and R (countrycode, on CRAN) to generate many commonly used country codes. Then follow the instructions for merging data into the PGE found in the “stata_pge.pdf” or “R_pge.pdf” files included in the data download.

The PGE Data

What about Russia and the rest of the former Soviet Union? Yugoslavia? Czechoslovakia? Pakistan? Sudan? Ethiopia? Why are there estimates for successor states before they actually existed?

For countries that have undergone partition, the PGE estimates for a given year include all of the origin country’s then-current territories. This means that for dates before partition, all of the once united territory is included: estimates for Sudan before 2011, for example, include present-day South Sudan.

The estimates for Ruritania, among others, have changed since the previous version. Why is that?

There are two reasons why estimates change from one version of the PGE to the next. The first reason is that we have incorporated new source survey data for the country. Adding more source data for a country, particularly when previously available data was very scant, holds the potential that the estimates will change.

How is Germany treated in the PGE? Where’s East Germany?

Germany is West Germany only before 1991 and (united) Germany from that point forward. The PGE includes no estimates for East Germany; we just haven’t found much to include in the source data. If you know of a survey with East German Ginis, email us with the details, and we’ll be happy to get it into the next version.