Economic Census of Island Areas

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2007 Methodology:

Basis of Reporting

The economic census is conducted on an establishment basis. A company operating at more than one location is required to file a separate report for each store, factory, shop, or other location. Each establishment is assigned a separate industry classification based on its primary activity and not that of its parent company.

Sources of Data

The 2007 Economic Census of Guam, the Commonwealth of the Northern Mariana Islands, Puerto Rico, and the U.S. Virgin Islands was conducted by mail. The economic census for American Samoa was conducted using a combination of mail and personal enumeration. Descriptions of the sources of data for the island areas follow:

1. Guam, the Commonwealth of the Northern Mariana Islands, Puerto Rico, and the U.S. Virgin Islands — A census form was mailed to all employer firms (employers of one person or more) in operation at any time during 2007 and classified as being within the scope of the census. One single report form was used to collect data for Guam, the Commonwealth of the Northern Mariana Islands, and the U.S. Virgin Islands. Nine separate report forms (Utilities, Transportation, and Warehousing; Construction; Manufacturing; Wholesale Trade; Retail Trade; Finance, Insurance, Real Estate, Rental and Leasing; Accommodation Services; Services; and General Schedule) with English and Spanish versions were used to collect data for Puerto Rico. Firms were instructed to return their completed report form by mail. A telephone follow-up was conducted to obtain information from selected firms that failed to return their report form.
2. The governments of Guam and the Commonwealth of the Northern Mariana Islands, under the provisions in Title 13 of the United States Code, Section 191(b), were responsible for contacting respondents about overdue census forms. The Chief Economist of the Department of Labor in Guam and the Director of the Central Statistics Division, Department of Commerce in the Commonwealth of the Northern Mariana Islands, supervised the local activities. Staff from the Census Bureau trained the project leaders, supervisors, and interviewers in Guam and the Commonwealth of the Northern Mariana Islands, respectively. Staff from the Department of Labor in Guam and the Department of Commerce in the Commonwealth of the Northern Mariana Islands, who worked with census data, were sworn to uphold the confidentiality of the data. The Census Bureau worked with the Department of Labor and the Central Statistics Division to collect information for nonrespondent establishments. Interviewers were instructed to contact establishments by telephone to obtain the required information. Personal interviews were conducted to obtain data from establishments that requested a personal visit or could not be contacted by telephone. Quality checks were performed to ensure that the necessary reports were obtained.
3. American Samoa — A combination of mail and personal enumeration was used to conduct the economic census of American Samoa. Data were collected for establishments with and without employees that were in operation during 2007. A single report form was used to collect data for American Samoa.
   
   
   1. Employer establishments — Establishments with payroll were sent a report form to be completed and returned to the Census Bureau by mail. A telephone follow-up was conducted to collect information for establishments that failed to answer the census.
   2. Nonemployer establishments — Data for nonemployer establishments were collected through personal enumeration. The Government of American Samoa collected the data under the provisions in Title 13 of the United States Code, Section 191(b). The Chief Statistician of the Statistics Division at the American Samoa Department of Commerce supervised the field enumeration and follow-up of nonemployer and nonrespondent employer establishments referred by the Census Bureau. All persons working with census data were sworn to maintain the confidentiality of Census Bureau information. Census Advisors trained the project leader as well as the interviewers. The advisors worked with local staff to ensure that Census Bureau standards and procedures were followed.
   3. American Samoa was divided into four enumeration zones — Manu'a Islands, Eastern, Central, and Western districts of Tutuila. Nonemployer establishments were identified from the American Samoa Government Business License List. Interviewers were provided with an assignment list that included the establishments assigned for interview and a labeled report form for each establishment listed. The interviewers obtained information about months in operation, physical location, sales/receipts, employment and payroll, expenses, kind of business, sales by class of customer, description of merchandise sold, construction work done, products produced, or services provided, legal form of organization, ownership status, and status of the establishment at the end of 2007. A consistency review was performed on every report form to ensure the accuracy of the reported data.

The report forms used to collect information for establishments in the island areas are available at the Get Forms Page.

A more detailed examination of census methodology is presented in the History of the 2007 Economic Census.

Industry Classification of Establishments

The classifications for all establishments are based on the North American Industry Classification System, United States, 2007 manual. The method of assigning classifications and the level of detail at which establishments are classified depends on whether a report form was obtained for the establishment.

• Establishments that returned a report form are classified on the basis of their self-designation, detail/description of product lines sold, type of construction work done, products produced, or services provided, and other industry-specific inquiries.
• Establishments that did not return a report form are classified on the basis of information obtained from previous survey data and administrative records of other government agencies.

Reliability of Data

All data compiled are subject to nonsampling errors. Nonsampling errors can be attributed to many sources during the development or execution of the census, such as,

• inability to identify all cases in the actual universe;
• definition and classification difficulties;
• differences in the interpretation of questions;
• errors in recording or coding the data obtained; and
• other errors of collection, response, coverage, processing, and estimation for missing or misreported data.

The accuracy of these tabulated data is determined by the joint effects of the various nonsampling errors. Explicit measures of the effects of these nonsampling errors are not available. However, precautionary steps were taken in all phases of the collection, processing, and tabulation of the data in an effort to minimize the effects of nonsampling errors.

The Census Bureau obtains limited information from administrative records of other federal agencies, such as information on employment and payroll. This information is used in conjunction with other information available to the Census Bureau to develop estimates for missing items on the report form or for establishments for which responses were not received in time for publication.

Disclosure

In accordance with federal law governing census reports (Title 13 of the United States Code, Section 9), no data are published that would disclose the operations of an individual establishment or business. However, the number of establishments in a kind-of-business classification is not considered a disclosure; therefore, this information may be released. Cell values that have a potential for revealing confidential information must be suppressed or have their values perturbed by using the "Noise Infusion" technique described below.

Noise Infusion

Noise infusion is a method of disclosure avoidance in which values for each firm are perturbed prior to table creation by applying a random noise multiplier to the magnitude data (i.e., characteristics such as receipts, payroll, and number of employees) for each company. Disclosure protection is accomplished in a manner that results in a relatively small change in the vast majority of cell values. For the 2007 Economic Census of Island Areas, each published cell value has an associated noise flag, indicating the relative amount of distortion in the cell value resulting from the perturbation of the data for the contributors to the cell. The flag for ‘low noise’ (G) indicates the cell value was changed by less than 2 percent with the application of noise, and the flag for ‘moderate noise’ (H) indicates the value was changed by 2 percent or more but less than 8 percent. Cells that have been changed by 8 percent or more are suppressed from the published tables. Additionally, other cells in the table may be suppressed for additional protection from disclosure or because the quality of the data does not meet publication standards. Though some of these suppressed cells may be derived by subtraction, the results are not official and may differ substantially from the true estimate.

The number of firms in a particular tabulation cell is not considered a disclosure of confidential information about an individual establishment; therefore, this information may be released without the infusion of noise. For an introduction to the noise confidentiality protection method, see Using Noise for Disclosure Limitation of Establishment Tabular Data [PDF 105KB] by Timothy Evans, Laura Zayatz, and John Slanta in the Journal of Official Statistics (1998).

Treatment of Nonresponse

Census report forms included two types of inquiries: general inquiries and industry-specific inquiries. Data for the general inquiries, which include location, kind of business or operation, payroll, and number of employees, were available from a combination of sources for all establishments. Data for industry-specific inquiries, tailored to particular kinds of business, were available only from those establishments that completed the appropriate inquiries on the report form.

For total nonresponse cases (report forms not returned) and missing items, the establishment's administrative records information was used in conjunction with industry averages, prior period data, and outside reference sources to estimate general and industry-specific inquiries. Large nonresponse cases were contacted to obtain information for general and industry-specific inquiries, as appropriate.

When reporting was incomplete or inadequate, product-line data for Puerto Rico wholesale and retail trades were expanded on the premise that data for those establishments not reporting this information are similar to product-line data for those establishments in the same kind of business that reported this information. In the 2007 Economic Census, the method used to account for nonresponse to product-line inquiries was to expand the total of reported data to represent 100 percent of the universe. Data presented for product lines were expanded in direct relationship to total sales of all establishments included in the category. A similar expansion was done using the number of establishments that reported product lines to adjust the establishment count.