Penn World Table Bleg

I postulate some tending from the increment empiricists out there.  If yous aren't i of them, halt reading.  Continuing volition be a waste product of your time.

For researchers studying economical growth, i of the criterion resources for cross-country information has been the Penn World Table.  My 1992 newspaper amongst David Romer in addition to David Weil (my most cited newspaper past times a large margin) used this resource, as accept numerous other papers inwards this literature.  In my intermediate macro book, I introduce a span of figures presenting some of these data.

Here's the problem: It seems that the information accept changed substantially in the most recent revision, in addition to I cannot figure out why.

My intermediate macro text shows a scatterplot of per capita income in addition to the investment part of GDP.  These 2 variables are strongly positively correlated.  When revising this figure amongst the newest data, I flora that the correlation declines substantially (though is all the same positive).  When I looked into the origin of the change, I found that the historical estimates of the investment part of gross domestic product accept changed, inwards some some cases past times a lot.

Let me plough over yous an example.  Take the investment share for Republic of Ghana inwards the yr 2000.  According to version 6.2 of the data, the investment share was about five percent.  In version 7.0, it was most 21 percent.  This is one of the larger changes I accept found, exactly it is not the exclusively terra firma for which at that topographic point are sizable changes inwards the reported investment part of GDP.

I sympathise that the changes may be related to novel information most the relative toll of investment goods.  But the changes seem also large to last explained in addition to then easily, although peradventure I am incorrect most this.  If anyone tin forcefulness out shed low-cal on the matter, I would last greatly appreciative.  Send me an electronic mail if yous tin forcefulness out help.
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Update: I accept non yet fully figured this out, exactly readers accept sent me some useful links.  If yous are interested, click here, here, in addition to here.
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