Frequently Asked Questions

Please choose from the list below:

Do I need any special software to run this CD-ROM?
What is on the 1997 VIUS Microdata CD-ROM?
What do you mean by "microdata"?
How do I use the microdata, and what can it do for me?
How can I find out what kind of data are captured by each data item (mnemonic)?
What is the data dictionary, and how can I print it out for use as a reference?
What is a PDF file?
What are pre-defined tables?
How do I create cross-tabulations?
What is nesting, and how does it work?
Can I save my tables as a dBase (*.dbf) or text file (*.txt)?
How do I export a table?
Is the extract (data) file available in a text or database format?
Are the 1997 VIUS questionnaires available to view or print for reference?
Can I obtain truck miles estimates with this CD-ROM?
Does this CD-ROM contain data about a truck's daily mileage or trip activity?
Can I use this CD-ROM to get information about particular carriers or fleet owners?
Can I access the previously released VIUS data on this CD-ROM?
Can I calculate the coefficients of variation for estimates not previously published?
Are data from the VIUS prior to 1997 available in electronic format?
How can I get more information about the VIUS program?

Note- External links will only work if an on-line browser is being used and you are connected to the Internet.

Do I need any special software to run this CD-ROM?
No, this CD-ROM comes with all the software needed to run the Ivation 20/20 Browser, as well as the necessary software to access all the documentation and files. For details on setting up this CD-ROM, go to the CD Setup page.
What is on the 1997 VIUS Microdata CD-ROM?
The 1997 VIUS Microdata CD-ROM contains a 77-MB ASCII microdata file with 104,545 records. Each record contains 397 data items (mnemonics) that describe a truck's physical and operational characteristics, as collected by the VIUS. In addition to the microdata file, the CD-ROM contains a data dictionary that describes each mnemonic. Also included are PDF files of previously released data from the 1997 VIUS, pre-defined tables of data not previously released from the 1997 VIUS, documentation highlighting the VIUS program, 1997 VIUS questionnaires, information on the CD-ROM setup, and a tutorial containing directions on performing common functions.
What do you mean by "microdata"?
The term "microdata" refers to the individual responses to the VIUS. The records are modified to avoid the possibility of identifying individual vehicles or owners.
How do I use the microdata, and what can it do for me?
The microdata can be used to generate your own customized tabulations from the 1997 VIUS. Go to the Tutorial for examples of how to generate tabulations.
How can I find out what kind of data are captured by each data item (mnemonic)?
There are four ways to find out the kind of data captured by each mnemonic. The first way is by viewing the list of mnemonics grouped by related topics. The second way is by viewing the data dictionary. Refer to question 6 for more information about either of these items. The third way is available when viewing the list of mnemonics used to create a cross-tabulation (while in the Ivation 20/20 Browser). Right click on any mnemonic and choose (left click) "Source Field Summary" to view. The fourth way is available when viewing any mnemonic in the table (extract) window. You will notice that the mnemonics being used in the table (extract) are underlined. Double left click on any underlined mnemonic to view. Refer to the Tutorial for examples.
What is the data dictionary, and how can I print it out for use as a reference?
The data dictionary is a text file that contains the mnemonics on this CD-ROM. Information for each mnemonic includes the length, the starting position in the ASCII microdata file, the amount of decimal places (if any), a description of what the mnemonic stands for, the question as it appears on the form (if applicable), a definition, the sample unit universe for the mnemonic, and the possible responses. The data dictionary can be viewed and printed using your browser. You can save the file to your personal computer by right clicking on the data dictionary link and then clicking on "save link as". You can then use software such as Microsoft Word or Notepad to view or print it. Please note that the data dictionary is at least 80 pages long when printed (depending on the program being used). When creating a cross-tabulation, the mnemonics to choose from will appear in alphabetic order. To view a list of the mnemonics grouped by related topics, as well as a brief description for what each mnemonic represents, click on the link provided (mnemonic list).
What is a PDF file?
PDF - Portable Document Format. PDF files were used on the VIUS Internet site: http://www.census.gov/svsd/www/97vehinv.html to publish state and U.S. data. These files are viewable using Adobe Acrobat, which is pre-loaded on this CD-ROM. To view any of the PDF files available, go to the Data page, or our web site link above.
What are pre-defined tables?
Pre-defined tables are tables that have already been created on this CD-ROM containing data not previously released from the 1997 VIUS. These tables were created to highlight data that had been available in the 1992 U.S. Summary, but dropped from the 1997 U.S. Summary for various reasons. These pre-defined tables also serve as an example of the types of cross-tabulations that can be created using this CD-ROM. To access these pre-defined tables, go to the Data page.
How do I create cross-tabulations?
Refer to the Tutorial for examples on how to create cross-tabulations.
What is nesting, and how does it work?
Nesting is using more than one mnemonic in a stub to further define your cross-tabulation. For example, if you wanted to conduct a "4 X (by) 1" cross-tab (i.e., body type X (by) major use X (by) miles per gallon X (by) total length for each state) you would use nesting. Refer to the Tutorial for examples on how to nest mnemonics.
Can I save my tables as a dBase (*.dbf) or text file (*.txt)?
Yes, after you have designed your table, you can save the output in the following formats: Data table (*.ivt), comma separated (*.csv), text file (*.txt), WKS worksheet (*.wks), WK1 worksheet (*.wk1), dBase file (*.dbf), or as Aremos TSD (*.tsd). To see an example of how to save your output in different formats, refer to the Tutorial.
How do I export a table?
Refer to the Tutorial for directions on how to export a table.
Is the extract (data) file available in a text or database format?
Yes. The extract file is available on this CD-ROM in both a text and database format. Both of these files are on this CD-ROM in a zipped file (VIUS.zip). When unzipped, the text file (mdf.txt) and the database file (VIUS.mdb) will be available for your use.
Are the 1997 VIUS questionnaires available to view or print for reference?
Yes, the two questionnaires used in the 1997 VIUS are available on this CD-ROM as PDF files, and can be viewed or printed for reference. The TC-9501 form was mailed to the registered owners of trucks in stratum 1 and 2. The TC-9502 form was mailed to the owners of trucks in stratum 3, 4, and 5. The questionnaires can be accessed by clicking on the links provided.
Can I obtain truck miles estimates with this CD-ROM?
Yes, in addition to calculating truck estimates, you can also calculate truck miles estimates. In order to do this, you must reset the assigned weights from trucks (EXPANF) to miles (WANNMIL). Once in the Ivation 20/20 Browser, select "Data" from the menu. Next select "Set weight field". The default on the CD-ROM will have the box for "Set weight field" checked with EXPANF highlighted. Change the highlighted field to WANNMIL and then choose "OK". You will now be able to run cross-tabulations based on truck miles. Remember to change the selected weight back to EXPANF for cross-tabulations based on truck counts. Refer to the Tutorial for an example of how to change the weight and create a cross-tabulation for truck miles estimates.
Note- You may have to adjust the width of the "Total" column in the Ivation software to view the entire number of truck miles.
Does this CD-ROM contain data about a truck's daily mileage or trip activity?
No, this CD-ROM provides estimates for a truck's annual and lifetime miles. Each record indicates the state in which the truck is registered, the state in which the truck is based, and whether the home base is inside or outside a Metropolitan Statistical Area (MSA).
Can I use this CD-ROM to get information about particular carriers or fleet owners?
No, the microdata records on this CD-ROM are modified to avoid the possibility of identifying individual vehicles or owners. We do not provide the Vehicle Identification Number (VIN) of the truck or the name/address of the registered owner.
Can I access the previously released VIUS data on this CD-ROM?
Only previously released 1997 VIUS data appear on this CD-ROM. These are available in PDF format located on the PDF page. PDF files for the 1992 program can be obtained through our web site: http://www.census.gov/prod/1/trans/92trkinv/92trkinv.html.
Can I calculate the coefficients of variation for estimates not previously published?
Yes, the procedure to manually approximate coefficients of variation can be found in Appendix A of the 1997 U.S. Summary PDF file.
Are data from the VIUS prior to 1997 available in electronic format?
Data from the 1992 program are available on CD-ROM. You may request a 1992 TIUS Microdata CD-ROM by visiting this web site: http://www.census.gov/mp/www/rom/msrom.html#Economic. Data prior to 1992 are not available in electronic format. You may request a one-off CD-ROM copy of the TIUS microdata computer tape (if available). There is no software on one-off CD-ROMs. One-off CD-ROMs are in ASCII format only, and take between 1 to 2 weeks to complete. Also, one-off CD-ROMs are extremely fragile and are easily damaged with a scratch or nick to its underside. Any questions regarding the sale, availability, or pricing of these one-off CD-ROMs should be directed to: webmaster or call Customer Services at 301-457-4100.
How can I get more information about the VIUS program?
For additional information about the VIUS program that is not found on this CD-ROM, please visit our web site at http://www.census.gov/econ/www/viusmain.html or visit the Contacts page.

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