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Getting Data In and Out of the Pool
Since pooled series are just ordinary series, you’re free to load them into EViews any way that you find convenient. But there are two data arrangements that are common: unstacked and stacked. These data arrangements correspond to the spreadsheet arrangements we saw in Spreadsheet Views earlier in the chapter. Unstacked data are read through a standard File/Open. (See Chapter 2, “EViews—Meet Data.”) EViews provides some special help for stacked data.
Importing Unstacked Data
Here’s an excerpt of an Excel spreadsheet with unstacked data.
Since we have ordinary series with conveniently chosen names, load in the spreadsheet in the usual way, create a pool object with suffixes CAN, FRA, etc., and bob’s your uncle.
Importing Stacked Data—The Direct Method
Here’s an excerpt of an Excel spreadsheet with stacked data—stacked by cross-section. We’ve hidden some of the rows so you can see the whole pattern. All the data for the first country appears first, stacked on top of the data for the second country, etc. While Y and POP appear in the first row, the country specific series names, such as YCAN, don’t appear.
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We want EViews to help out by attaching the identifiers in the first column to the series names beginning with Y and POP. With the pool window active, choose the menu
Proc/Import Pool data (ASCII,XLS,WK?)…. Fill out the dialog with the names of the series to import, as in the example to the right. Hit
and EViews will get everything properly attached.
Not surprisingly, stacked by date is the flipped-on- the-side version of stacked by cross-section. Here’s an excerpt. The same Proc/Import Pool data (ASCII,XLS,WK?)… command works fine—just choose the By Date radio button instead of By Cross-section.
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Importing Stacked Data—The Indirect Method
Sometimes, a little indirection makes life go more smoothly. In the case at hand, it’s often easier to simply read your data into EViews by the methods you’re already familiar with (for example, we might read in our data by drag- and-dropping the file onto the EViews desktop and clicking on 
to accept the defaults) and then work with it in panel form (see Chapter 11, “Panel—What’s My Line?”), or transform it into pooled form using
Proc/Reshape Current Page/Unstack in New Page…. and filling out the Workfile Unstack dialog as shown.
Click 
and you have a new page set
up in pooled form. In fact, to help out EViews has even set up a pool object for you.
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Exporting Stacked Data
Typically, unstacked data are easier to operate on, but sometimes stacked data are easier for humans to read. The inverse of Proc/Import
Pool data (ASCII,XLS,WK?)… is
Proc/Export Pool data (ASCII,XLS,WK?)…. Choose By Date or By Cross-section and away you go.
Hint: EViews includes the “?” in the series name in the output file. You might choose to manually delete the “?” in the exported file to improve the appearance of the output.
Exporting Stacked Data—A Little Indirection Here Too
Not surprisingly, there’s an indirect method for exporting, too. To stack data in a new page in preparation for using any of the usual export tools, choose
Proc/Reshape Current Page/Stack in New Page…. In the Workfile Stack dialog, enter the name of the pool object. Click 
for a nicely stacked page.
Quick Review—Pools
The pool feature lets you analyze multiple series observed for the same variable, such as GDP series for a number of countries. You can pool the data in a regression with common
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coefficients for all countries. You can also allow for individual coefficients by cross-section or by period for any variable. Fixed and random effect estimators are built-in. And because pooled series are just plain old series with a clever naming convention, all of the EViews features are directly available. See Chapter 11, “Panel—What’s My Line?” for a different approach to two dimensional data.
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