Frequently Asked Questions

Data Release

What is the difference between restricted-use data and public-use data files?

There are several types of modifications on the public-use files that will cause it to differ from the restricted-use files:

• Outliers will be top- or bottom- coded. This prevents identification of unique schools without affecting overall data quality.


• Certain schools identified as at risk for disclosure have a small percent of noise introduced in those variables that pose a risk for disclosure. Again, this does not affect overall data quality.


• Certain variables with too few cases and a sparse distribution are suppressed in the public-use files, but are available in the restricted-use files.


• Certain continuous variables are modified into categorical variables, and certain categorical variables have their categories collapsed in the public-use file. While this protects from disclosure risk, these variables can still be used in different kinds of analysis such as regression analysis.

How will the difference in public-use files and restricted-use files impact analysts?

For most users, the public-use files provide all the data and variables required for most analyses. Both the public- and restricted-use files provide data at the individual child, teacher, and school levels. However, some users may require the restricted file. For example, those researchers examining certain rare sub-populations such as the disabled, or children with specific non-English home languages and those interested in examining the type and number of hours of kindergarten programs offered in schools will find that the restricted files have a few more variables. In many cases, even though the detailed information on the restricted-use files may be of interest, the sample sizes are often too small for these analyses. However, the modifications used to avoid the identification of schools, teachers, and children do not affect the overall data quality and most researchers should be able to find all that they need in the public-use files. Overall, few variables have been suppressed. For any user uncertain of their needs, NCES recommends first examining the public-use files to verify if the needs of the researcher can be met using those data files.

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