GDP per Capita in Panel Data: Must the base year be the same for all cross-sections? I'm trying to run a small project using time series in panel data. One of the variables used is the GDP per capita for a few countries (the countries are the cross-sections). Is there a problem if the base year for a few countries is different? Say for example, Spain's series has 2005 as base year while Germany's series 2010 as base year. Does this cause any sort of problems?
Thank you in advance.
Base rates account for the change in value of a currency that happens overtime because of inflation.
Not only do the base rates need to be the same, but if you are including all of these in the same panel, then the currencies need to be in the same unit as well, otherwise, the different country GDP's are not comparable.
Fortunately, most of the big international databases with GDP time series usually have multiple versions, with different base years, and converted to common currencies (usually USD) that you can use to assemble what you need.  Just a few places to start you off:
FRED
World Bank WDI
OECD Data
Note: for GDP data, these sites often present data from the same sources