There are two types of data sources used for the U.S. Import and Export Price survey. The first type of data are administrative data that form the basis of the sample selection process. For an explanation of these data sources and how they are used, see the design section. The second type of data are the price data used for index calculation. Price data are predominantly collected through the U.S. Import and Export Price survey. In some instances, price data are collected through other administrative or secondary data sources.
The first two stages of sample selection result in a list of establishments and the number and type of items. The sample is based on trade transactions that occurred in the past. For more information on these two stages, see the design section. The third and final stage of the sampling process requires updated item selection by a BLS field economist with the cooperation of the company representative at a sampled establishment. A successful interview with a sampled establishment results in a more detailed list of current items that are actually traded and establishes the items that best represent the mix of goods for the sampled establishment identified during the item sampling stage. The subsequent collection of the monthly price for each item, if traded, forms the basis of price changes that are aggregated into the final price indexes.
For the final stage of the sampling process, a BLS field economist meets with a company representative of a sampled establishment and conducts the initial price survey. The selection of the actual items that constitute the market basket occurs at this stage. During the personal interview, the field economist asks a series of questions to identify the actual products presently being traded and confirms that the establishment is actually still trading in the sampled-product categories. The field economist describes the types of items required for the market basket using detailed product category or classification group descriptions, and the respondent provides examples of commonly traded items with the respective prices and share of total company trade. Items that are traded at least once a year are chosen for the categories required to fill out the survey. The choices depend on the information available starting with actual trade dollar value, then estimated trade dollar value, and finally an estimate on trade dollar value ranking among potential choices. If no information is known about the dollar value, then items are chosen randomly. The field economist records item and price information and price-determining characteristics which include size, composition, country of origin, range of capabilities, and transaction terms; and instructs the survey respondent on the monthly data collection process. Once items are selected, those items are then initiated into the market basket that is then repriced on a monthly basis.
Upon the initiation of an item into the market basket, the BLS national office staff coordinates continued monthly price collection with the company respondent. (For more information on the types of goods and services that are covered by the U.S. Import and Export Price survey, see the concepts section.) Survey respondents may transmit the monthly transaction price of the items selected for the survey by a secure internet site or by telephone if more convenient for the respondent. BLS staff may contact the survey respondent to assure price information is submitted by the deadline or to request clarification and validate changes to item characteristics or prices. All reporting is voluntary and confidential, in accordance with the BLS report to the Office of Management and Budget’s confidential information protection and statistical efficiency act (CIPSEA).
Respondents provide prices for items based on actual transactions that occur as close as possible to the first day of the month for which the data are to be published. The recorded price is the actual transaction price for which an item is purchased or sold. The transaction price ideally accounts for discounts and surcharges paid or charged; duties on imports are not counted as part of the price. For more information on what is included in the transaction price, see the concepts section.
A number of prices collected come from intercompany trade, production sharing, or cases for which a company can only provide an average price. For each of those cases, the price still represents the transaction price at the point an item crosses the border. Intercompany trade occurs when the price of items that are purchased or sold are determined through trade within a company or between affiliates of related companies. The price reported may be determined by market-related factors, but that is not always the case. Production sharing is product manufacture shared between two (or more) independent companies or various affiliated units of the same company that are located in different countries. In addition, average prices provided by respondents are occasionally used when items are homogenous and that is the only price they can provide.
Price information may be collected on a less-than monthly schedule if the item is not traded monthly, if the price is set by contract and does not change in intervening months, or to alleviate burden on the respondent. If an item is not traded in a given month, a respondent may provide an estimated price based on what the item price would have been if the item were traded. When the item price is set by contract, the transaction price is carried forward during the duration of the contract until a new price is set. For other methods of handling missing prices when a respondent cannot provide an estimate, see the calculation section.
Some commodity categories are not collected directly through the U.S. Import and Export Price survey. Administrative data sources provide prices on petroleum imports and grain exports. The U.S. Energy Information Administration (EIA) provides administrative data for all imports of crude petroleum products. The U.S. Department of Agriculture Farm Service Agency provides data for most grain exports. Secondary data sources are used to collect import and export prices for diamonds and metals, air passenger fares, and petroleum exports. All administrative and secondary source data sets are collected on a monthly basis; the same index calculation methods are applied to directly collected and administrative or secondary source data.
Once received, transaction prices undergo review and verification to validate the quality of responses. When data collected are incomplete or show changes to important data elements, such as the item description, price-determining characteristics, and survey respondent information, additional validation is needed. Industry analysts complete this additional validation by contacting the company respondent to ensure that the item priced remains consistent from month to month. For information on how substitutions, replacements, and quality adjustments are handled, see the calculation section. Industry analysts might also contact respondents in the case of a nonresponse or if the price change leads to an index percent change surpassing a set maximum or minimum value. The maximum and minimum values are set at 2.5 standard deviations from the average percent change for the index historically.
The Bureau of Labor Statistics (BLS) is strongly committed to protecting the confidentiality of information provided by respondents and ensuring that it is used only for statistical purposes. This pledge of confidentiality means that only BLS employees and agents, such as contract employees or employees of state agencies working on statistical programs under BLS agreements, will ever have access to respondent information. The limitations on use of the data for statistical purposes means that BLS will combine respondent information to produce descriptions, estimates, and analyses regarding the state of the economy without identifying the individual information provided.