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Overseas Merchandise Trade: November 2009
Embargoed until 10:45am  –  07 January 2010
Technical notes


billion 1,000 million. 
capital goods Produced assets used repeatedly or continuously, for longer than one year, in industrial production processes. Examples are machinery, trucks and aircraft.
cif Cost of goods, including insurance and freight to New Zealand.
consumption goods Goods used (without further transformation in industrial production processes) by households, government or non-profit institutions serving households.
fob Free on board (the value of goods at New Zealand ports before export).
Infoshare Free-of-charge online tool that gives you access to a range of time-series data.
intermediate goods Goods used up or transformed in industrial production processes.
merchandise trade Exports or imports of goods that alter the nation's stock of material resources. Includes goods leased for a year or more. Excludes goods for repair.
provisional Statistics for the latest three months are provisional, to allow for the inclusion of late data and amendments.
re-exports Merchandise exports that were earlier imported into New Zealand and comprise less than 50 percent New Zealand content by value.
vfd Value for duty (the value of imports before insurance and freight costs are added).

Data source

Data is obtained from export and import entry documents lodged with the New Zealand Customs Service (NZCS). The data is processed and passed to Statistics NZ for further editing and compilation.


Exports (including re-exports) are valued fob (free on board) and are shown in New Zealand dollars. Estimated values are used for goods that are not already sold at the time of export entry lodgement.

Imports are valued at cif (cost including insurance and freight) and are shown in New Zealand dollars.

Trade balance values are calculated by deducting imports (cif) from exports (fob). These two valuations are not entirely comparable, because the cif valuation includes insurance and freight to New Zealand while the fob valuation excludes insurance and freight from New Zealand. However, imports in tables 1 and 2 are also shown at the vfd (value for duty) level, which excludes the insurance and freight component.

Exchange rates

Export values given in foreign currencies are converted by Statistics NZ into New Zealand dollars, using weekly exchange rates when the statistics are compiled. For exports, a rise in the New Zealand dollar has a downward influence on prices, quantities, and values.

Import values are converted from foreign currencies when import documents are processed by NZCS. The exchange rates used are set by NZCS each fortnight. These rates are prepared 11 days prior to the start of the fortnight, so have a lag of 11 to 25 days compared with the daily rates published by the Reserve Bank. For imports, a rise in the New Zealand dollar has a downward influence on prices and an upward influence on quantities. The combined influence on values can be either positive or negative.

Time of recording


From the August 1997 reference month, exports are compiled by date of export. Previously, exports were generally compiled according to date of clearance by NZCS. This meant that some goods were allocated to the month following their actual month of export. Exports up to July 1997 that were not processed until August 1997 were assigned to the month of August 1997.

From 1 March 2004, NZCS do not allow goods to be loaded for export until an export entry has been lodged and cleared. A study undertaken in 2001/02 indicated that export entries not being lodged might account for between 1 and 3 percent of exports at that time. There is a possibility that the change in NZCS processes may have reduced this undercoverage, although this has not been quantified.


Imports are generally compiled by date of entry clearance by NZCS. NZCS entries are required from up to five days before, to 20 working days after, arrival of goods into New Zealand. The exception to this rule is for crude oil imports, which can have entries lodged later than 20 working days after entry into New Zealand.

Crude oil values for the latest month are estimated using actual quantities and country of origin data (provided by NZCS, based on information from the refinery at Marsden Point), together with estimated prices. These estimates for crude oil are replaced once actual entries are lodged with NZCS.

While all entries are provisional for the latest three months, and have the potential to be changed by the importer/exporter within this period, changes are not common, and generally do not have a material impact on the results. However, New Zealand has only a few ships carrying crude oil arriving each month, and each ship represents a high proportion of the monthly total of imported crude oil. Any variation in the data for crude oil resulting from a later lodgement date can result in a significant revision to the value. Once actual lodgements are received by Statistics NZ from NZCS, the value for crude oil can be regarded as robust.

There were 21 working days in November 2009, compared with 20 in November 2008.

Commodity classification

Commodities are classified according to the New Zealand Harmonised System Classification (NZHSC).

The NZHSC was revised from the January 2007 reference month, to incorporate changes promulgated by the World Customs Organization. Details can be found in the Overseas Merchandise Trade: January 2007 Hot Off the Press released on 26 February 2007.

Standard International Trade Classification

The Standard International Trade Classification (SITC) is an output classification (using Harmonised System (HS) codes at the 6-digit level as building blocks), designed by the United Nations as an analytical tool for economic analysis, which includes some simple implications regarding level of processing. Published figures are at a high level of aggregation; more disaggregated information is available on Infoshare. For customised jobs using the SITC Rev 4 classification, contact customer services at:

Broad economic category groups

Broad economic category (BEC) groups are arranged, as far as practicable, to align with the System of National Accounts’ three basic classes: capital goods, intermediate goods, and consumption goods. Commodities in BEC groups are categorised on the basis of their main end use. This means, for example, that all video recorders are treated as consumption goods even though some are used in business. Similarly, all helicopters are treated as transport equipment even though some are military goods (and are treated as such in the National Accounts).

Trend series

Time series can be split into trend, seasonal, and irregular components. Seasonal adjustment removes the seasonal component, while trend estimation removes the seasonal and irregular components. Trend estimates reveal the underlying direction of movement in a series and are used to identify turning points.

The trend series are calculated using X-12-ARIMA, which adjusts for outlying values and uses a centred moving average. The length of the centred moving average is selected automatically and can be 9, 13, or 23 months, depending on the relative variability of the irregular component compared with the trend. A long moving average has the effect of smoothing the trend series but slowing the response to underlying changes in growth rates, while a short moving average produces a trend series that is less smooth but quicker to identify turning points.

To improve estimation of the underlying movement, the imports trend is calculated after removal of individual import items that have cif values of $100 million or more, such as large aircraft and ships. The trade balance trend is calculated by subtracting the imports trend from the exports trend.

Trend figures are recalculated each month. The use of new monthly data means that previously published trend estimates are subject to revision. These revisions mainly affect the latest months, and can be large if a trade value is initially treated as an outlier but is later found to be part of the underlying trend.

Seasonally adjusted series

These are calculated for calendar quarters, using X-12-ARIMA, and published in the March, June, September, and December releases.

Seasonal adjustment removes the estimated impact of regular seasonal events, such as pre-Christmas purchasing, from time series. This makes the figures for adjacent periods more comparable. Seasonally adjusted figures are estimates and are subject to revision each quarter, with the largest changes generally occurring in the latest quarters.

Further information is on the Statistics NZ website.  

Confidential items

Under Section 37A (d) of the Statistics Act, the Government Statistician may disclose details of external trade, movement of ships, and cargo handled at ports. However, Statistics New Zealand understands that the release of merchandise trade commodity information can, in some cases, place commercially sensitive information in the public domain. Statistics New Zealand is able to provide a limited form of confidential status for commodity items (at the discretion of the Government Statistician), upon application by a company or business.

In practice, all confidential HS codes are aggregated into the code 9809.00.00.00 in order to protect their confidentiality and to maintain total export and import values. Any aggregations of HS codes below this level, which encompass confidential 10-digit codes, exclude the confidential value(s) for these codes.

The only aggregates that include the confidential codes are total exports, total imports, and the total exports and imports by country.


Overseas Merchandise Trade (OMT) statistics are compiled in close accordance with the United Nations' International Merchandise Trade Statistics Concepts and Definitions. OMT data, after adjustment, is used in the Balance of Payments and National Accounts. The adjustments are for coverage, timing, valuation, and classification, and are explained in the Balance of Payments – Sources and Methods 2004 publication.

Additional information

Other information on overseas trade is available from:

  • Statistics NZ website:
  • Infoshare
  • Key Statistics – the quarterly statistical publication
  • The New Zealand Official Yearbook.

Related Hot Off the Press releases are:

  • Overseas Cargo Statistics: ISSN 1178-2838
  • Overseas Trade Indexes – Prices: ISSN 1178-0339
  • Overseas Trade Indexes – Volumes: ISSN 1178-0347
  • Balance of Payments (quarterly): ISSN 1178-0215
  • Balance of Payments (annual): ISSN 1178-0223
  • Economic Survey of Manufacturing: ISSN 1178-024X.

More information

For more information, follow the link from the Technical notes of this release on the Statistics NZ website.


Information obtained from Statistics NZ may be freely used, reproduced, or quoted unless otherwise specified. In all cases Statistics NZ must be acknowledged as the source.


While care has been used in processing, analysing, and extracting information, Statistics NZ gives no warranty that the information supplied is free from error. Statistics NZ shall not be liable for any loss suffered through the use, directly or indirectly, of any information, product, or service.


Timed statistical releases are delivered using postal and electronic services provided by third parties. Delivery of these releases may be delayed by circumstances outside the control of Statistics NZ. Statistics NZ accepts no responsibility for any such delays.

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