This means that there is some amount of uncertainty in any result obtained using NRI data. Each NRI estimate has a different level of precision and the standard error for each estimate may be found in the NRI data tables. The margin of error is 1.96 times the estimated standard error, and can be used to construct a 95 percent confidence interval for the estimate. Data collected for the 1997 NRI update were collected using photo interpretation, field office records, historical records and data, a variety of ancillary materials, and a limited number of onsite visits. For a glossary of terms used in NRI data collection and interpretation, click here .
All definitions are available in the glossary.
In addition, this December 2000 revision of the 1997 NRI data updates information released in December 1999 and corrects a computer error discovered in March 2000. For More National NRI Background information click here .