EXTRACT -- Frequently Asked Questions



1. Can I use EXTRACT on a CD-ROM I access across a network?
2. What is the difference between selecting items and selecting records?
3. How do I get data for all counties (or other type of area) at once?
4. Why might I get a blank file selection screen?
5. What do I do if I get a RUN ERROR?
6. What do I do if the installation program has a RUN TIME ERROR R6003?
7. Can I program EXTRACT to do the same operations for multiple states?
8. How can I get help using EXTRACT?


1. Can I use EXTRACT on a CD-ROM I access across a network?

If you are accessing a CD-ROM on a network using Novell Netware, you need to add the following line to your NET.CFG file:
READ ONLY COMPATIBILITY=ON

Failure to do so will keep EXTRACT from reading files on the networked CD-ROM, yeilding error messages like
proc CATSELE line 72 undefined identifier Alias


2. What is the difference between selecting items and selecting records?

In the normal display mode, selecting items is a matter of selecting columns, and selecting records is a matter of selecting rows or lines in the display. We don't use that terminology because it is always possible to Toggle to the "rowwise" display in which both items and records are displayed on successive, annotated rows.

Whether a given variable is selected using records or items depends on how the file has been structured. When you are at the main menu, press to get a help screen that explains the difference between selecting items and selecting records for the particular file you are working with.


3. How do I get data for all counties (or other type of area) at once?

Some users intuitively feel that they ought to put an X next to every county name in order to select all counties. They realize that doesn't work when the Select Records menu allows no more than 14 or so specific values to be checked off.

Selecting records is a matter of restricting what records display. If you want "all" of something, then you don't want to restrict along that dimension. You need to figure out what differentiates the records you want from the records you don't.

Many files have a summary level or record type code, such as GEOTYPE in the 1992 Economic Census or SUMLEV in the 1990 STF's, that allows you to differentiate among different types of geographic areas. On the STF's, for example, you select all county-level records by selecting SUMLEV code 050.

4. Why might I get a blank file selection screen?

The file selection screen will be blank if EXTRACT can't read the directory of your CD-ROM or can't find any of the type of files you have selected. This can happen if the CD-ROM drive is empty, the CD-ROM is not fully inserted, the wrong CD-ROM is in the drive, or the wrong drive letter has been specified for the CD- ROM.


5. How can I avoid RUN ERRORs?

EXTRACT requires 500 to 520k of RAM. If you don't know how much memory is available, run the CHKDSK program included with DOS; the last line of screen output tells you how much memory is available. If you have less than 500,000 or so, you may need to reboot with network drivers or TSRs (terminate-and- stay- resident programs) removed or loaded into high memory.

The points in the program where you are most likely to encounter memory problems are on the drive selection screen when the system is trying to offer you a menu of master catalogs; when you are accessing a particularly long definition, such as the STF 3 table locator; or when you are creating a extract file in .PRN format with headers and footers.


6. What do I do if the installation program has a RUN TIME ERROR R6003?

EXTRACT's INSTALL utility does not work with certain recent Windows operating systems. If you get a run time error, simply follow these alternate installation instructions instead.


7. Can I program EXTRACT to do the same operations for multiple states?

EXTRACT is not a programming language, and has no capability to save procedures from one session or file to another. Since some databases present data for different states in different files (e.g., STF 3a, CBP), you have to repeat record selection and other steps a tedious 51 times to get data for all states.

dBASE and other general database packages do have programming capabilities, and it may be preferable to use one of them--if you have one--for the most repetitive tasks, after you have become familiar with the census files through EXTRACT. ALLSTATE.PRG is a sample program written for dBASE III+ that builds a national file of data for places of 2500 or more inhabitants from the separate state specific files from STF 1a. The program prompts the user to insert multiple CD-ROMs in succession. You can modify the code to do analogous operations with other state-specific files from the STFs, CBP, agriculture census, etc.


8. How can I get help using EXTRACT?

A help line is available for EXTRACT users at 301-457-4151. There are a few things you can do if you think you have encountered a program bug.


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revised 6/27/96