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Archive-name: auto/sci.econ/EconData-FTP-site


                                Guide to

                                EconData

                  A Source of Economic Time Series Data
                     from the University of Maryland
                              1992 July 22


This Guide tells how to use the EconData service of the University of
Maryland.  Several hundred thousand economic time series, produced by
the U.S. Government and distributed by the government in a variety of
formats and media, have been put into a standard, highly efficient,
easy-to-use form for personal computers and made publicly available
through this service.  These series include various national accounts,
labor information, price indices, current business indicators and
industrial production, information on states and regions, and
international data.  A more complete list of the series covered can be
found in the file CONTENTS.DOC.  These series are all in the form of
banks for the G regression and model building program and its public
domain version, PDG.  The DOS version of PDG and the banks can be
downloaded from the University's computer systems by anyone connected to
Internet or, more slowly, by telephone.  The data have been put in this
form by the INFORUM research group in the Economics Department.  The
dissemination by computer network is made possible by the Computer
Science Center.


HOW TO GET THE DATA

EconData may accessed in three ways:

  1.   Through Internet using an ftp (file transfer protocol) for
       "anonymous" login
  2.   Through Internet using a Telnet package to use the "info"
       interface (intended to make the downloading process easier).
  3.   By modem and telephone at 1200 or 2400 baud.

The first two are far faster than the third, so we begin by describing
them.


Internet with the anonymous login.

Internet, is a computer network linking most of the major research
universities in the United States and many other countries.  If you have
obtained this document by way of Internet, you must know what is in this
section.  If, however, you obtained it by mail or by dial-up modem or
through the University of Maryland's interactive INFO system, you will
find the method described here vastly faster.

Exactly how one connects with Internet is different at each site and
must be learned from the local network administrator.  All the rest of
how to use EconData is the same everywhere.  Generally, a user at a PC
connected to a local network that connects to Internet has a command to
make the connection with "ftp" -- a File Transfer Protocol.  Let us say
that this command has the name "ftpcall", though it will almost
certainly be something else.  You would then type:

  ftpcall info.umd.edu
That command connects you to the "info" machine at the University of
Maryland.  You will see on your screen:

  user name:
  ftp>

You then type:

  user anonymous

You are then asked for a password.  It will be your identification while
connected, so your name would be a good choice.  After giving the
password, you again get the "ftp>" prompt.  Reply with 

  binary
  cd /info/EconData/Instructions

Do not forget the capital letters in "EconData" and "Instructions". 
Then, the first time you are connected, do:

  get readme.doc
  get gbanks.doc
  get guide.doc
  get contents.doc
  cd ../Tools
  get pkz110.exe  (if you do not already have PKZip version 1.1 or
  higher)
  get unzip.exe
  get unzip.doc
  get dezip20.com
  get pdgarc.exe
  get pdgsup.exe
  bye

Those instructions will obtain the essential tools you need and a
demonstration bank.  After studying the "contents.doc" file, you can
come back for particular banks.  Let us suppose you decide that you want
nipaq.zip, the quarterly national accounts.  It is in the
Data/USNational/Accounts
directory, so you again repeat the above procedure as through the line
"binary" and then do:

  cd /info/EconData/Data
  get nipaq.zip
  bye

You can then follow the example below for using nipaq.zip


Internet via Telnet with the INFO interface.

A telnet program is one which provides terminal emulation over the
Internet to a user, who can either be connected directly with a PC or
via a mini or mainframe computer.  As with FTP there are many versions
of Telnet software and specific questions about its use should be
directed to your system administrator.  While the speed of transfer may
of may not be affected by using Telnet rather than FTP, a connection
made with Telnet has an advantage in that it offers the users full
screen menus.  These menus significantly improve the user friendliness
of the INFO bulletin board and EconData, especially for first time
users.  

For the purposes of this explanation, we will assume that your Telnet
program is simply called telnet (as it often is).  The command to issue
Telnet should be something like this:

  telnet info.umd.edu

When connected you should be given a login prompt, such as:
  
  login:

you should reply:

  info

This login connects you to a more user-friendly interface which allows
you to view the documentation files before the downloading.  Learn what
the various commands available to you do by using the arrow keys to
select the command and then tapping the '?' key.  You first want to
"View" EconData.  Then you want to "X-fer" the files listed above.  When
you choose "X-fer", you will be asked to choose the type of transfer
protocol.  You will probably want to choose either the FTP or TFTP
protocols, the choice of which will depend upon on your particular
Telnet program.


Telephone and modem connection.

If not connected to internet, you can use your modem for a dial-up call
to download some of the files.  (Some data files are so large that this
method of downloading may require more than the maximum 90 minute
connection allowed by the system.)  Follow these steps:

  1.   Start your communications program.  Set the terminal emulation as
       vt100 if possible, otherwise note how it is set.  Dial
       301-403-4333 with the following communications parameters:  baud
       2400 if possible, otherwise 1200 or 300; 8 data bits, no parity,
       1 stop bit.   If you have a 9600 baud modem the number is 301-
       403-4444 with the same settings as above.

  2.   After the terminal is connected, tap the 'Enter' or 'Return' key
       every second until the annex prompt appears.

  3.   At the "annex" prompt, type
       telnet info.umd.edu

  4.   At the "login" prompt, type 
       info

  5.   To the question about terminal type, answer "vt100" or the other
       type which you set your communication program to emulate.  

  6.   Learn what the various commands available to you do by using the
       arrow keys to select the command and then tapping the '?' key. 
       You first want to "View" EconData.  Then you want to "X-fer" the
       files listed above. You will want to use the Kermit protocol.

  7.   To leave the system, select Quit on the menu.  That will take you
       back to the "annex" prompt.  Reply "ha" to this prompt to
       "hangup".

THE FIRST FILES YOU NEED

The very first time you connect, you should transfer the following
files:


In the Instructions subdirectory:

  README.DOC     Brief notes on recent changes in EconData
  CONTENTS.DOC   A description of the subdirectories of EconData and the
                 files contained in those subdirectories
  GUIDE.DOC    The current version of this document.  If the date at the
               top is the same as the date of the file, you presumably
               do not need the file, since you are looking at it.  This
               document, explaining how to use these economic time
               series.  The same material is available as a file for
               WordPerfect 5.1 as GUIDE.WP.

In the Tools subdirectory:

  PDGARC.EXE   The public domain version of the G regression package,
               necessary for using the data files.
  PDGSUP.EXE   The supplementary programs for the G regression package,
               used for making tables and manipulating data.
  PKZ110.EXE   The PKZip archival package.  If the files you want end in
               ".zip", you need this program or some other compatible
               program to de-archive them.  PKZip is shareware, and a
               modest registration is required for legal use beyond an
               initial trial period.  We started off with DWC because it
               was public domain and out-performed the well-known PKArc. 
               However, PKZip gives significantly greater compression,
               so we have gradually switching to it.)  

PKZip and PKUNZip are the packages that we used and tested to create the
archive you see here.  However, we have also made available two public
domain programs that were designed to strictly de-archive Zipped files. 
We have made these available to you if you want to save on license fee,
but to you, but we have not fully tested them.  If you are interested,
you might be able to use the following programs instead of PKZip:

  DEZIP20.COM
  UNZIP.EXE
  UNZIP.DOC

DE-ARCHIVING

Except for a few ASCII files ending in the ".doc" extension, all files
on EconData have been archived with PKZIP and have the ".zip" extension. 
They must be de-archived before they can be used. 

For PKZIP, the process is slightly different.  At the DOS prompt, just
type 

  PKZ110

and the one file will explode into a number of files, one of which is
PKUNZIP.EXE and others are documentation and registration information. 
To de-archive the file xxxx.zip, just type

  pkunzip xxxx

The commands for the public domain alternatives to pkunzip are very
similar.  You should refer to the accompanying documentation.

PUBLIC DOMAIN G

All of the time-series are in the form of banks for G and PDG.  PDG is
contained in the file PDGARC.EXE, and important supplementary programs
are in PDGSUP.EXE.  These are "must" files for the initial download.

Once you have downloaded these files and you are back on your own
computer, create a pdg subdirectory by typing: 

  c:
  cd \
  md pdg
  cd pdg

Now move or copy to this directory the PDGARC.EXE, and PDGSUP.EXE files. 
De-archive PDG by typing:

  pdgarc 
  pdgsup 

You should now backup the PDGARC.EXE, PDGSUP.EXE files to diskette.  You
may then delete PDGARC.EXE and PDGSUP.EXE from your hard disk to save
space.  

Now, edit your autoexec.bat file to include c:\pdg in the path.  Also,
your config.sys file should have the lines

  FILES = 20
  BUFFERS = 20

The "20's" may be replaced with larger numbers.  Probably your
config.sys file is already fine; if not, modify it and reboot. Now it is
time to try out PDG. Do:

  cd \pdg
  pdg demo

You will get a demonstration of PDG's functions.


USING PDG WITH THE ECONOMIC TIME-SERIES DATA

Once PDG is in the path, you can access it from any subdirectory.  Now
you simply need to download a time-series of interest from the Data
subdirectory in Econdata.

For illustration purposes, we will assume that you have downloaded the
quarterly National Income and Product Accounts time-series, NIPAQ.ZIP. 
On you own computer, you need to set up a subdirectory for this data. 
This is done by typing:

  cd \
  md nipaq
  cd nipaq

Now copy or move the NIPAQ.ZIP file to this directory, and type:

  pkunzip nipaq
You may then delete NIPAQ.ZIP.  Note that if you are using one of the
public domain alternatives to PKUNZIP, then you would replace that
programs name for "pkunzip" in the above example.

Each time-series has its own G configuration file, G.CFG, specific to
that series.  Provided that each series is kept in a different
subdirectory, then when you start PDG, the G.CFG file will automatically
assign this bank.  You start PDG by typing:

  pdg

Answer the opening question with a 'Enter', and then, at the  :  prompt,
do:

  look

and you may now explore the quarterly NIPA accounts.

Of course, it is possible to have all of the time-series data in one
subdirectory; but then you must specify which bank you would like to
look at once you are in PDG.  You do this at any : prompt by typing:

  hbk nipaq

If you are using PDG in another directory, you can assign this bank by
the G or PDG command:

  hbk \nipaq\nipaq

These steps should get you started.  The "demo" will introduce you to
the basic functions of PDG; the "help" files are extensive and may be
printed out.  There are also interactive lessons in the material you
have downloaded. The book "The Craft of Economic Modeling" by Clopper
Almon (Ginn Press) gives many examples of the use of G.


AVAILABLE DATA

Read the file CONTENTS.DOC for a list of currently available data.


COMMON QUESTIONS

  Q.   Do I have to download a whole huge file every time it is updated?
  A.   No, just download a small file with the updates and run a simple
       program to update the old large file from the small new one. 
       Suppose you have downloaded nipaq, the quarterly  national
       accounts, and a new quarter rolls around.  You will then soon
       find a file in the Data directory named newnipaq.zip.  Download
       it to the same directory with your nipaq bank.  Then do

          splice nipaq newnipaq revnipaq

       SPLICE is a program in the pdgsup.exe file which you have
       installed into the pdg  directory.  This command will create a
       new compressed bank named revnipaq.  Start PDG and assign it with
       the command

          hbk revnipaq

       Then examine a few series to insure that everything has worked
       properly.  Then exit PDG, delete nipaq.cin and nipaq.cbk and do

          ren revnipaq.* nipaq.*

       Your nipaq bank is now updated.

  Q.   Can I download an individual series?
  A.   No.  Only whole banks can be moved.  But whole banks now move
       faster than individual series did a few years ago.  

  Q.   How large are the banks and how long does it take to download
       one?
  A.   A typical bank is 200 - 400K bytes, though some reach 2 or 3
       megabytes.  We experience  a file transfer rate of about 5 or 6 K
       bytes per second in downloading via Internet from  systems at
       other universities.  (The local rate is some 45 K per second). 
       Thus, the  complete annual national accounts, 5,600 series, each
       back to 1929 or whenever it begins,  occupies 425 K bytes and
       would require about 75 to 90 seconds. Since downloading a 1.44
       Megabyte diskette of data requires only about 3 minutes, there is
       little reason to mail diskettes among sites connected to
       Internet.  Download by dial-up telephone is much slower.  The
       theoretical maximum rate is .24 K per second, so a file will take
       20 to 25  times as long by dial-up as it does via Internet.

  Q.   How current are the data?  
  A.   Banks which we can update from the Commerce Department's Economic
       Bulletin Board  (EBB) are updated within a few days of release of
       new data.  These include the quarterly  National Income and
       Product Accounts, the Business Conditions Indicators, the Blue 
       Pages of the Survey of Current Business, and the Indexes of
       Industrial Production.  The  Federal Reserve cooperates by
       lending us a Flow of Funds tape when it appears, so this bank is
       also very up-to-date.  Other data we have to purchase.  In
       particular, the Bureau of Labor Statistics has explicitly refused
       any cooperation other than selling us the tapes.  Consequently,
       these files are updated only when we have a particular need to do
       so.  That is at least once a year but seldom monthly.

  Q.   What is the advantage of EconData over EBB?
  A.   The Commerce EBB is primarily composed of "documents," often
       press releases, not banks.  Almost every file is in a different
       format.  There is no standard way to get the data into an
       analytical program.  Nor is there any standard way to update a
       previous file with new information.  On EconData, every bank is
       in the format of a G data bank.  Updating is easy.  To update our
       banks from the EBB, we have had to write C-programs  -- a
       different one for every EBB file -- to put the EBB material into
       a standard form.  Writing these programs was a tiresome bother.  
       We have put them in the "Tools" directory of EconData, in case we
       should not be quick enough for you in getting the file  ready
       some month.  We have urged the EBB staff to at least offer our
       banks to their users.  They have declined to do so because they
       accept only files from U.S. Government agencies.  We then urged
       agencies to use these banks to submit data to the EBB.  The 
       Federal Reserve submits the industrial production indexes in the
       form of an ASCII file  for input into PDG.  The staff of other
       agencies, though expressing personal admiration  of the programs,
       have been apprehensive that making the data so easy to use might
       constitute competition with private industry. 
  Q.   How hard are the data to use, once I get them?
  A.   If you are using PDG or G as your main analysis program, you have
       only to type a three-letter command plus the bank name to assign
       the bank.  Then the "look"  command allows you to search for the
       series you want, graph it or display it numerically.  A brief
       command, followed by the names of the variables you want, will
       write the series  to ascii files or 1-2-3 worksheet files. 
       Nearly any program can read them in this form.  

  Q.   What else do PDG and G do?
  A.   PDG will do algebraic and functional (such as logarithmic)
       transformations of series and  convert a series from monthly to
       quarterly or from quarterly to annual periodicity -- and vice
       versa, approximately.  You can bring in your own data and make
       banks that have series selected from your own data and one or
       more of the EconData banks.  PDG will graph data in a variety of
       ways -- lines (up to seven) with user-controlled line size,
       style, and marking, multiple-scale graphs, bar graphs, stacked
       bars, parallel bars, scatter graphs,  scatter graphs with
       connected points, semi-logarithmic graphs, and so on.  It allows
       on-screen annotation of graphs and can "remember" the annotations
       that were made on screen so that when the same graph is repeated
       with updated data, the annotation will automatically appear.  It
       will do screen dump prints to most printers.  (Full G also
       supports PostScript printers, TIFF files, and HP- compatible
       printers with downloaded fonts.)  A companion program makes
       tables that can include growth rates and annual averages of
       monthly or quarterly data.  PDG does ordinary least squares
       regression, regression with "soft" or "stochastic" constraints,
       and distributed lags via soft constraints.  Full G, for $95, adds
       Hildreth-Lu correction for autocorrelation, ARIMA methods,
       seemingly unrelated regression and stacked regression with
       constraints across equations, non-linear regression, automatic
       Chow tests, and pooled time-series and cross-section regression. 
       With its sister program Build, it can build simultaneous equation
       models with hundreds of equations.  Both G and PDG have extensive
       on-line documentation.  There are versions of both programs in
       French, Italian, Spanish, Russian, and Chinese.  The Italian
       version is being officially used in data dissemination.

  Q.   What is the form of the data banks?  How do they pack so much
       data into so little  space? Can they be used without PDG or G?
  A.   The precise form is described, byte-by-byte, in the gbanks.doc
       file in the Instructions directory of EconData.  While one cannot
       simply look at the banks with the DOS "type"  command or a text
       editor, there would be no problem for authors of other data
       handling  programs to read the G banks.  Basically, for each
       series, the frequency, starting date, and number of decimal
       places are recorded.  The decimal point is then shifted to the
       right to give a sequence of integers, and the first differences
       of these integers are taken. If the differences are all between
       -32K and +32K, then the series can be stored with perfect
       accuracy as an initial value and then these differences, stored
       as 2-byte integers.  Otherwise, the storage defaults to 4-byte
       floating point.  G and PDG can use the series in this form; they
       reconstitute each series as needed.  For transmission, the
       resulting banks have been further compressed by putting them
       through PKZIP, data compression and archiving programs.  PKZIP
       are available in the Tools directory of EconData, along with some
       public domain programs which seem to be very good at unzipping
       ZIP files.
  Q.   How is EconData supported?
  A.   The INFORUM research group has developed many of these data banks
       for its own use in  building the most comprehensive interindustry
       models of the U.S. economy.  It has a PC  with a 9-track tape
       drive, the essential piece of hardware to bridge the gap between
       the  PC world and the 9-track tape world which most government
       data suppliers still live in.  Since INFORUM is not in the
       business of selling data, it has been willing to make these banks
       available to other academic researchers through Internet. 
       Several other groups have asked INFORUM to put particular bodies
       of data into this form and have agreed to let the result be
       placed on EconData.  Other groups at the University of Maryland
       have  also contributed interest and support.  Further
       contributions -- particularly if already in  G-bank form -- would
       be most welcome.