Order CD-ROM of 1997 NRI "Raw" Sample Point Data:
NRI data for four points in time (1982, 1987, 1992, and 1997) are completely comparable
and consistent from year to year so that the data reflect true trends and temporal analyses
can be made. When making comparisons with 1982, 1987, and/or 1992 data, the new (1997)
NRI
database must be used. Originally released 1982, 1987, and 1992 data may not be consistent
with the new database. The historical 1982, 1987, and 1992 data were updated to reflect
1997 technical criteria and protocols as part of the 1997 NRI inventory process. The 1997
NRI database should be considered self-contained in that respect. The 1992 dataset is no
longer being supported.
NRI data were collected at more than 800,000 sample sites nationwide.
This is a very large sample, which means that the data
can be legitimately used to analyze issues at many geographic levels --
national, regional, State, and sub-State (multi-county).
The NRI was not designed to provide statistical
estimates for counties or 8-digit hydrologic units; however, examining
the data at various geographic levels, including county or 8-digit
hydrologic unit, is a legitimate analytical technique for gaining additional
insight into the database. Anyone who intends to work with NRI data,
especially at the county or 8-digit hydrologic unit scales, should read
carefully the technical guidance as to the suitability and limitations of
the data and the error-estimation procedures.
The CD includes data files of the natural resource data for each sample point, along
with the associated georeferences of FIPS code, Hydrologic Unit Code, and
Major Land Resource Area Code. The data are presented in comma delimited
ASCII format and the user will need to import the data into software
applications of their choosing in order to manipulate the data and generate
estimates and statistical errors. "A Guide
for Users of 1997 NRI Data Files" and reference
information is provided.
This document is also available in Adobe Acrobat format.
"A Guide for Users of 1997
NRI Data Files" (1.4 MB)
In order to properly use the CD data, the user must:
- Have knowledge of statistical sample surveys and how to generate estimates and statistical errors for survey data.
- Provide database management system software with statistical software application. *
- Import the data into a software application. **
- Have sufficient hard disk capacity (estimate for national data set is: 2.5 GB)
* Most common statistical packages will not provide appropriate estimates for the
NRI stratified cluster sampling design.
However, there are several commercial software packages available to the data analyst that may be used.
These include: SAS ® (Release 8.2),
SUDAAN ®,
and WesVar ®.
Additionally, DOS software packages, PC CARP and SUPERCARP, can be
obtained from: Statistical Laboratory, Iowa State University, 219
Snedecor Hall, Ames, Iowa 50011; telephone (515) 294-9773.
** There are some limited MS® ACCESS database and SAS® tools
provided as a courtesy to users who already own this software, but the
software itself is not provided.
Use of product names (or trade names) does not imply endorsement of
products (or software systems) by the USDA Natural Resources
Conservation Service.
Please be aware that this CD does NOT contain:
- Tables of natural resource data estimates nor associated statistical errors.
- The actual geographic location of sample points in the inventory (these are confidential).
- Spatial (geographic) data layers (some are available online).
- Soils database (efforts are underway toward linking NRI data with the National Soils Information System for future use).
Order 1997 NRI Data
Data for the 48 conterminous United States, Hawaii, Puerto Rico, and the U.S. Virgin
Islands are contained on a single CD.
Order the CD online
.
The processing fee for each CD is $50.00.
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