Behind the Numbers U.S. Trade in the World Economy (1992) / Chapter Skim
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Appendix F: Options for the Use of Sampling to Collect Merchandise Trade Data
Appendix F: Options for the Use of Sampling to Collect Merchandise Trade Data
Pages 245-257
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From page 245... ...
The three options are not necessarily mutually exclusive: it would be possible, for example, to use a combination of cutoff and probability sampling of trade documents; another possibility would be to use an establishment sample to produce preliminary estimates of a few monthly aggregates, while continuing to rely on the present system for detailed data. The first two options relate solely to the production of merchandise trade data based on the official import and export documents.
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From page 246... ...
(Data exchange with Canada covers about 20 percent of total value of exports; the other 20 percent is reported~ electronically.) For import and export transactions reported electronically, the "sampling" is even simpler: it consists of computer instructions to omit any transactions below the cutoffs from all tabulations.
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From page 247... ...
~ A Census Bureau memorandum tHuang, 1987) states that "the validity of the estimated low value factors is in doubt." The use of cutoff sampling provides exporters with an opportunity to escape the SED filing requirement.
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From page 248... ...
PROBABILITY SAMPLING OF TRADE DOCUMENTS In general terms, probability sampling requires that all units belonging to a defined universe have a known, nonzero chance of selection. Large units, if desired, can be given a selection prob
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From page 249... ...
The latter approach would be a combination of probability and cutoff sampling. Starting in 1953 and continuing until 1982 for imports and 1985 for exports, the Census Bureau selected probability samples of Tow-value import and export transactions, processed these transactions, and used the data in its monthly estimates.
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From page 250... ...
· Sampling paper export documents to produce more timely preliminary estimates of the key merchandise trade statistics, but processing all documents, possibly on a delayed schedule, to eventually produce the present level of detail. This option would add substantially to the present cost of the program.
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From page 251... ...
provide monthly estimates of acceptable reliability for an unknown number, x, of data cells, with x lying somewhere between 12 and the more than 200,000 export data cells for which data are published for made available in CD-ROM format) monthly.
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From page 252... ...
There are several general considerations for designing such a study: · The study should provide information on the reliability of monthly, quarterly, and annual estimates for the same data cells. With fixed sampling fractions, the accumulation of sample data over more than one month can provide estimates of acceptable reliability for longer periods.
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From page 253... ...
There are at least two possibilities directly relevant to a decision on whether to use extensive probability sampling of non-Canadian paper export documents. The first would be to redesign the SED to incorporate machinereadable codes to allow fully or partly automated sorting and batching of incoming documents consistent with the different kinds of treatment they require in the sample selection procedures, ant!
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From page 254... ...
To reproduce the full detail available from the present system of official trade documents, it would be necessary to ask a large sample of enterprises to report full data for each of their import and export transactions or, at best, to report combined data for transactions cluring the reference period for the same country, commodity, and method of transportation. Alternatively, establishments with large numbers of transactions could be asked to report data for only a sample of their transactions.
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From page 255... ...
Even to provide summary data on a monthly basis might turn out to be a costly and time-consuming effort for the sample enterprises and one they would be unwilling to undertake. (Under current law, Census Bureau establishment surveys that require more frequent than annual reporting cannot be made mandatory.J What kinds of merchandise trade data could reasonably be proclucect by collecting data from a sample of enterprises?
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From page 256... ...
Computer files of import and export records can be matched to KIN records from the economic censuses and the Census Bureau's Standard Statistical Establishment List to produce listings of importers and exporters- with their names and addresses, establishment detail, and characteristics, such as industry cIassification and volume of imports and exports that could be uses! to design an efficient sample.
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From page 257... ...
CONCLUSIONS A new establishment sample is clearly not a viable option in the short term to replace the present system of compiling merchandise trade data from official trade documents, even if the amount of detailed data required monthly could be reduced somewhat. Substantial time and resources would be needed to decide what kind of information and how much detail could and would be reported on a monthly basis by importers and exporters.
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