The economic census results are based on a complete enumeration of all known employer establishments in some sectors and a sample of establishments in other sectors.

To determine whether the results are based on a complete enumeration or a sample of establishments, see the methodology text for the sector of interest. In American FactFinder, click on the "i" button to the right of the table title to find this text.

Some surveys and censuses capture data on an establishment basis and tabulate data up to firms, while others capture data on a firm basis to start with.

To confirm how the data are collected, data users need to review:

• the methodology text because classification of an entire firm (and all its establishments) may be quite different from the classification of each establishment of the firm. In American FactFinder, click on the "i" button to the right of the table title to find this text.

Some surveys and censuses allow businesses to self-classify, while others collect raw data that is then used to classify the business.

To confirm how establishments are classified, data users need to review:

• the introductory and methodology text because results of self-classification may be quite different from Census Bureau-performed classification. In American FactFinder, click on the "i" button to the right of the table title to find this text.

Disclosure processing is done separately for each census and survey.

Data users need to be aware of this:

• because it is possible to see different disclosure patterns for seemingly similar data across two or more surveys.