Reliability of Estimates
Estimates in published tables are based on data from the Annual Survey of Manufactures. To maintain confidentiality, no estimates are published that would disclose the operations of an individual firm. The total error of a published estimate may be considered to be comprised of sampling error and nonsampling error. Individuals who use 2000 Annual Survey of Manufactures estimates to create new estimates should cite the Census Bureau as the source of only the original estimates. See technical documentation for additional information on the Annual Survey of Manufactures.Confidentiality Statement Title 13 of the United States Code authorizes the Census Bureau to conduct censuses and surveys. Section 9 of the same Title requires that any information collected from the public under the authority of Title 13 be maintained as confidential. Section 214 of Title 13 and Sections 3559 and 3571 of Title 18 of the United States Code provide for the imposition of penalties of up to five years in prison and up to $250,000 in fines for wrongful disclosure of confidential census information. In accordance with Title 13, no estimates are published that would disclose the operations of an individual firm.
The Census Bureau's internal Disclosure Review Board sets the confidentiality rules for all data releases. A checklist approach is used to ensure that all potential risks to the confidentiality of the data are considered and addressed.
Disclosure Statement A disclosure of data occurs when an individual can use published statistical information to identify either an individual or firm that has provided information under a pledge of confidentiality. Disclosure limitation is the process used to protect the confidentiality of the survey data provided by an individual or firm. Using disclosure limitation procedures, the Census Bureau modifies or removes the characteristics that put confidential information at risk for disclosure. Although it may appear that a table shows information about a specific individual or business, the Census Bureau has taken steps to disguise or suppress the original data while making sure the results are still useful. The techniques used by the Census Bureau to protect confidentiality in tabulations vary, depending on the type of data.
Total Error Statement The total error of an estimate based on a sample survey is the difference between the estimate and the true population value that it estimates. The true population value is usually unknown.
Sampling Error The sampling error of an estimate based on a sample survey is the difference between the estimate and the result that would be obtained from a complete census conducted under the same survey conditions. This error occurs because characteristics differ among sampling units in the population and only a subset of the population is measured in a sample survey. The particular sample used in this survey is one of a large number of samples of the same size that could have been selected using the same design. Because each unit in the sampling frame had a known probability of being selected into the sample, it was possible to estimate the sampling variability of the survey estimates. The Census Bureau recommends that individuals using Annual Survey of Manufactures estimates incorporate this information into their analyses, as sampling error could affect the conclusions drawn from the estimates.
Nonsampling Error The nonsampling error of an estimate based on a sample survey encompasses all factors other than sampling error that contribute to the total error of the estimate. This error may also be present in censuses and may be attributed to many sources: inability to obtain information on all units in the sample; response errors; differences in the interpretation of the questions; mistakes in coding or keying the data obtained; and other errors of collection, response, coverage, and processing. Additional nonsampling error may have been introduced by the method used to adjust the survey estimates using results of the 1997 Economic Census. Although no direct measurement of the potential biases due to nonsampling error was obtained, precautionary steps were taken in all phases of the collection, processing, and tabulation of the data in an effort to minimize their influence. The Census Bureau recommends that individuals using Annual Survey of Manufactures estimates incorporate this information into their analysis, as nonsampling error could affect the conclusions drawn from the estimates.
