Confidentiality: The Census Bureau is required by Section 9 of Title 13 United States Code to keep respondents' information confidential and can use the information only to produce statistics. The Census Bureau is not permitted to publicly release a respondent's information in a way that could identify a business, organization, or institution. Per the Federal Cybersecurity Enhancement Act of 2015, submitted data are protected from cybersecurity risks through screening of the systems that transmit data.
Disclosure Avoidance: Disclosure is the release of data that reveals information or permits deduction of information about a particular survey unit through the release of either tables or microdata. Disclosure avoidance is the process used to protect each survey unit's identity and data from disclosure. Using disclosure avoidance procedures, the Census Bureau modifies or removes the characteristics that put information at risk of disclosure. Although it may appear that a table shows information about a specific survey unit, the Census Bureau has taken steps to disguise or suppress a unit's data that may be "at risk" of disclosure while making sure the results are still useful.
The Census Bureau has reviewed this data product to ensure appropriate access, use, and disclosure avoidance protection of the confidential source data (Project No. P-7503922, Disclosure Review Board (DRB) approval number: CBDRB-FY24-0002).
Sampling Frame: Companies, parts of companies (defined by Employer Identification Numbers, or EINs), and single-unit establishments (also defined by EINs) that are located in the United States, have paid employees, and are classified as merchant wholesalers, excluding manufacturer's sales branches and offices. The EIN is the identifier employer businesses use to report Social Security payroll withholdings to the Federal government. Read more [PDF] about the MWTS Sampling Frame.
Sample Design and Size: The MWTS uses a stratified, one-stage design with primary strata defined by industry (e.g., Motor Vehicle and Motor Vehicle Parts, Furniture and Home Furnishings, Grocery, etc.). There are 42 primary strata. The primary strata are substratified into 4, 7, 10, or 13 annual sales size strata. The largest sales size stratum within each industry stratum consists of companies, all of which are selected with certainty (sampling weight equal to one). The other strata are populated by EINs. Sample sizes are computed to meet multiple coefficient of variation constraints on estimated annual sales and end-of-year inventory totals. Constraints are specified at detailed industry levels and at broad industry levels up to the total wholesale level. Sampling weights range from 1 to 500. Units are selected independently between strata using simple random sampling without replacement within the size substrata. The sample consists of approximately 1,700 certainty companies and 2,500 noncertainty companies. Updates to the sample are made on a quarterly basis to account for new businesses, deaths, and other changes to the universe. Read more [PDF] about how the MWTS sample is stratified, selected, and maintained.
Data Collection: Data are collected by mail, fax, internet, and telephone. Response is voluntary. Questionnaires are mailed each month and request data for the month just ending.
Data Items Requested: Data items requested include monthly sales, end-of-month inventories, number of establishments covered by the report, and the ending date of the report period if the data provided are for a period other than the calendar month.
Nonresponse: Data are imputed for unit nonresponse, item nonresponse, and for reported data that fail edits. Imputed data are based on responses from similar-sized units classified in the same industry. Read more [PDF] about how nonresponse is handled on the MWTS.
Estimation and Sampling Variance: Preliminary estimates are published approximately 40 days after the data month and are revised approximately 30 days later. Total estimates are equivalent to Horvitz-Thompson estimates, that is, they are computed by summing weighted data (reported or imputed) where the weight for a given unit is the reciprocal its probability of being selected into the sample. Variances are estimated using the method of random groups and are used to determine if measured changes are statistically significant. Read more [PDF] about how the MWTS arrives at its estimates and the reliabilty of using those estimates.
Benchmarking: Monthly estimates are benchmarked to annual survey estimates that have been adjusted using the latest available Economic Census results. Month-to-month change estimates are computed from the benchmarked total estimates.
Seasonal Adjustment: Estimates are adjusted for seasonal variation and trading-day differences using the Census Bureau's X-13 ARIMA-SEATS program using the X-11 filter-based adjustment procedure. Read more about how the MWTS uses seasonal adjustments to produce high quality statistics about our nation's economy.
Important Uses of Results: The Bureau of Economic Analysis (BEA) is the primary Federal user of data collected in the MWTS. BEA uses this information to prepare the national income and product accounts, input-output accounts, and gross domestic product.
