Nonsampling Error: The data are subject to various nonsampling error:
An incomplete listing of all school systems in the United States would result in coverage errors. The Census Bureau tries to mitigate coverage error by performing checks against various other sources of school system data: the NPEFS state totals, NCES listing, and the Census Bureau's Governments Integrated Directory. We also request information from the State Department of Education in each state.
Nonresponse error results from incomplete responses to items on the forms. In order to produce a complete data set, the Census Bureau attempts to call back respondents, uses alternative sources for the data, or imputes for missing data.
Various other nonsampling errors include: response error which results from inaccurate reporting of the data, keying error which results from mistakes when entering the data, and classification error which results from placing the data in the wrong categories. All of these errors are mitigated by editing of the individual unit data. Both the central collector and Census Bureau perform data quality checks.
The section on Data Processing describes our efforts through editing and imputation to mitigate errors due to nonresponse, keying, reporting errors, etc.