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Information about the Overseas Trade Indexes (Volumes) |
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Availability
| Valid From: .. | 01/01/1891 |
| To: .. | Ongoing |
| Frequency: .. | Quarterly |
Design
Purpose: The Overseas Merchandise Trade Price and Volume Indexes measure changes in the levels of prices and volumes of imports and exports of merchandise trade to and from New Zealand. The Overseas Services Trade Price Indexes measure changes in the levels of prices of imports and exports of services trade to and from New Zealand.
General Information ..General Information ..
What the price and volume indexes measure
These indexes are numerical series that indicate how a set of prices and volumes has changed between time periods. Each index measures changes in the level of prices and volumes rather than the actual prices and quantities. It is the change between two index numbers that is important. An individual index number has no meaning.
The overseas merchandise trade price indexes measure changes in the levels of prices and volumes of imports and exports of merchandise trade to and from New Zealand, on both a quarterly and an annual basis. The overseas services trade indexes measure changes in price levels of services to and from New Zealand on a quarterly basis.
Price and volume measurement relates to the decomposition of transaction values in current prices into their price and volume components. In principle, the price components should include changes arising solely from price changes, while all other changes (relating to quantity, quality and compositional changes) should be included in the volume components. The aim is to analyse which changes in aggregates are due to price movements, and which are due to volume changes. This is also referred to as a "constant price' measurement, implying the analysis of economic transactions valued at fixed prices.
Index coverage
The merchandise trade indexes include all commodities classified as merchandise trade, although the export indexes exclude re-exports, bunkering, ships' stores and passengers' effects.
The System of National Accounts 1993 (SNA'93) provides the conceptual base for the services indexes. It establishes the range of services that should be included in the indexes and key practices, for example the treatment of insurance.
Source of information - merchandise trade
Value and quantity data used for calculating the merchandise price indexes are derived from Statistics New Zealand's overseas merchandise trade statistics, which are in turn processed from export and import entry documents lodged with the New Zealand Customs Service by exporters, importers and their agents.
Data are classified using the Harmonised System (HS) classification for processing customs entries and publishing overseas trade statistics. There are over 18,600 10-digit items in the HS classification.
HS 10-digit item by country unit values are derived from Statistics New Zealand's overseas trade statistics. Quarterly item by country unit values are calculated by dividing the total value of an HS item, exported or imported during the quarter, by the total quantity of the item exported or imported during the quarter. These unit values are then extensively edited, with outliers removed before use in trade index calculations.
Unit values provide suitable indicators of price change for basic, homogeneous commodities not subject to ongoing quality change. However, unit values do not provide good indicators of price change for heterogeneous goods such as elaborately transformed goods, technically complex goods or goods subject to rapid quality change. Unit values have been selectively supplemented with prices collected directly from importers and exporters, and by international price indexes.
Directly surveyed prices
Prices are collected directly from importers and exporters for selected goods that are regularly imported or exported in the same form to the same or similar specification. These items may not have a specified unit of quantity or may fall under an HS code with a heterogeneous description. Directly surveyed prices are collected from importers and exporters via the Commodity Price Survey used for the Producers Price Index.
Directly surveyed prices were first collected in the June 2002 quarter, so they contribute to movements for the September 2002 and subsequent quarters.
The process of adding to the pool of directly surveyed prices is an ongoing one and is part of the ongoing overseas merchandise trade index quality assurance programme.
International price indexes
International price indexes are used selectively as a proxy to measure price change faced by importers for goods that are irregularly imported (for example public transport equipment), imported to one-off specifications (for example, telephonic and telegraphic apparatus) and technically complex goods subject to rapid quality change (for example computer equipment).
The following table lists the areas of the HS classification where international price indexes have been used and the type of index selected as a proxy for change in prices faced by New Zealand importers. Most use has been made of the US Producer Price Index (PPI), with some use of the US HS Export Price Index (EPI). In both cases, monthly international price index numbers have been converted to quarterly index numbers and then exchange-rate adjusted using the New Zealand Customs Service rates of exchange.
The following table lists the main goods for which international price indexes are currently being used in the import indexes.
| HS Chapter | Goods | International Price Index |
| 84 | Mechanical machinery | |
| Printing machinery | US producer price index | |
| Computer equipment | US producer price index | |
| Computer and office equipment parts and accessories | US producer price index | |
| 85 | Non-electrical machinery | |
| Telephonic and telegraphic apparatus | US HS export price index | |
| Cellular phones | US producer price index | |
| Radio-telephonic parts | US HS export price index | |
| 86 | Railway equipment | US producer price index |
| 87 | Vehicles other than railway equipment | Minor use of US HS export price index |
| 88 | Aircraft | US producer price index |
| 89 | Ships | US producer price index |
The US PPI indexes that are used for computer equipment, parts and accessories are compiled using hedonic quality adjustment techniques designed to remove the effect of quality improvements and isolate pure price change. The US PPI indexes for computer equipment, parts and accessories used in the imports price index are lagged one quarter, to reflect a potential delay from the time that new technology is available domestically in the US to the time it is imported to New Zealand. The US computer indexes that are used in the merchandise imports price index and the one-quarter lag are both broadly in line with the approach that has been used for some time for quarterly constant price imports in Gross Domestic Product (GDP).
Adjustment to unit values for imported cars
The calculation of price movements for the main HS 10-digit item codes for cars differs from the unit value calculation used for other items in the overseas trade indexes. The used-car codes have previous June quarter and current quarter unit values calculated for each year of manufacture. The new car codes have unit values calculated for each of the main makes of car recorded under the codes. Movements in these unit values are weighted by the value of cars imported for each year of manufacture and make of car, respectively, to give Paasche, Laspeyres and Fisher indexes at the HS 10-digit item by country level.
The method was introduced in the June 2002 quarter to reduce the effect of new frontal impact standards, which reduced the number of pre-1996 used cars being imported, on the age distribution of used-car imports.
The dollar value of the car items treated in this way accounted for 8.9 percent of the total dollar value of imports in the year to June 2003.
Source of information – services trade
Value data used in calculating the weights for the service indexes are derived from Statistics New Zealand's Balance of Payments data, which are processed from various surveys operated by the Balance of Payments Division.
Pricing information used for calculating the indexes is obtained from Statistics New Zealand's Commodity Price Survey. The Commodity Price Survey collects prices for approximately 13,000 individual items. The items are collected by postal survey from about 3,000 respondents and from international price indexes. Prices are generally collected each quarter with the price on the 15th of the middle month of the quarter measured for domestic prices. Prices may be obtained quarterly or annually depending on the nature of the item. Much of the pricing for the import services indexes is from international price indexes. The collection of these prices (index numbers) depends on the frequency and timeliness of their publication. If they are published monthly, the middle month of the quarter is used; however, in some cases the prices are lagged a month or quarter if the value for the relevant period is not available in time.
Basis of valuation
The merchandise export indexes are calculated using New Zealand dollar free on board (fob) values. Export fob values represent actual or estimated transaction prices of goods, including costs incurred in delivering goods on board ships and aircraft at New Zealand ports of export. Values given in foreign currencies are converted by Statistics New Zealand into New Zealand dollars using weekly exchange rates when the statistics are compiled. This means that any hedging will generally not be reflected in the merchandise import and export price indexes.
The merchandise import indexes use New Zealand dollar value for duty (vfd) values. Prior to the September 2003 quarter, the merchandise import indexes used cost, insurance and freight (cif) values, which represented the value of goods plus the insurance and freight costs associated with bringing the goods to New Zealand ports of entry. Import vfd values represent the value of goods excluding the cost of freight and insurance. The vfd valuation for imports is recommended in the System of National Accounts 1993 (SNA 93) and is used in the New Zealand national accounts.
Vfd values are converted from foreign currencies when import documents are processed by the New Zealand Customs Service. The Customs rates of exchange are prepared 11 days prior to the effective date and are then applied for two weeks. Therefore the exchange rate used in the imports prices will be 11 to 25 days old when it is used in imports documentation. This means that the Customs exchange rate, and thus the imports prices, will be slower to show the impact of changes in the exchange rate than the Reserve Bank rates and the export prices.
Merchandise import price indexes are not directly affected by changes in the rates of duty payable on imported goods, as vfd values do not include duty. Therefore, the phased reduction in tariffs that has occurred in recent years has not had a direct downward influence on the import price indexes.
The services price indexes use New Zealand dollar values for both the exports and imports. Exchange rates used in the calculation of the services indexes differ from those used for the merchandise indexes. Prices collected in foreign currencies are converted using the exchange rate supplied by WestpacTrust for the 15th day of the middle month of the quarter for the relevant currencies. The foreign currencies used in the services indexes are the US dollar, Australian dollar, Fijian dollar, Japanese yen and the United Kingdom pound.
Effect of exchange rate movements
Changes in export and import price levels reflect movements in both exchange rates and in the actual foreign currency and New Zealand dollar prices that goods are bought and sold for. A decline in the value of the New Zealand dollar has an upward influence on both export and import price levels, while a rise in the value of the dollar has a downward impact on export and import price levels.
Index type and calculation
Merchandise trade
The merchandise index series are of the chain-linked Fisher Ideal type. The calculation of a Fisher Ideal index involves first calculating two indexes. One, the Laspeyres, is base-weighted and uses expenditures from an earlier period to weight price or volume movements. The other, the Paasche, is current-weighted and uses expenditures from a current period to weight price or volume movements. The Laspeyres and Paasche indexes are then averaged by calculating the geometric mean (that is, the square root) of the two indexes to give the Fisher Ideal index. In the majority of situations covered by index numbers, price and quantity changes are negatively correlated. In such cases, Laspeyres indexes tend systematically to record greater increases than Paasche indexes, with the gap between them tending to widen over time.
The merchandise index series have a June quarter price reference period, and are linked to the index for the June quarter of each year. There are annual expenditure weight reference periods for both the Laspeyres (previous June year) and Paasche (year to each quarter) components of the index.
The price index methodology involves:
- Calculating Laspeyres and Paasche price indexes for the current quarter on the previous June quarter.
- Calculating Fisher Ideal price indexes for the current quarter on the previous June quarter (as the geometric mean, or square root, of the Laspeyres and Paasche price indexes calculated in step 1).
- Linking the Fisher Ideal price index for the current quarter (calculated in step 2) to the index for the previous June quarter, to provide a continuous quarterly time series.
The Laspeyres and Paasche volume indexes for the current quarter on the previous June quarter are calculated by deflating the change in dollar value from the previous June quarter to the current quarter by the Paasche and Laspeyres price indexes, respectively (calculated in step 1 above). Steps 2 and 3 are repeated as above, using volume (rather than price) indexes.
The annual price indexes are calculated as volume index-weighted averages of the four component quarter price indexes, and the annual volume indexes as the simple average of the four component quarterly volume indexes.
Expenditure weights are assigned at the HS 10-digit item by country level. Item and index weights are not fixed. They vary from quarter to quarter and from year to year as the relative values of goods New Zealand exports and imports change.
Services trade
The services indexes are an annually chain-linked Laspeyres price index series. The weights are determined by the relative importance of services and businesses within the service industry. Information from various surveys, censuses and other sources are used to determine the weights.
Expression base
The merchandise index series expression base is the quarter ended June 2002 (=1000).
The merchandise terms of trade index expression base is the quarter ended June 2002 (=1000).
The services price indexes expression base is the quarter ended June 1997 (=1000).
The services terms of trade index expression base is the quarter ended June 1997 (=1000).
What the terms of trade index measures
The overseas terms of trade indexes measure the changing volume of imports that can be funded by a fixed volume of New Zealand's exports.
How the terms of trade are calculated
The merchandise terms of trade index is calculated as the ratio of the total export price index to the total import price index, and then presented on an expression base of the quarter ended June 2002 (=1000).
The services terms of trade index is calculated as the ratio of the total services export price index to the total services import price index, with the June 1997 quarter used as the expression base.
An index value above (or below) 1000 indicates that the terms of trade are more (or less) favourable than in the base period.
An increase in the terms of trade index indicates that the real purchasing power of exports has increased, while a decrease indicates a drop in the purchasing power of exports.
Effect of exchange rate movements on terms of trade
A decline in the value of the New Zealand dollar has an upward influence on both export and import price levels, and a strengthening of the dollar has a downward impact on prices of both exports and imports. This means that any effect on the terms of trade in either case is likely to be minor and limited to situations where the New Zealand dollar has weakened or strengthened against a particular currency, and there is a significant imbalance in the values of exports and imports transacted in, or with prices determined by, that currency.
Broad Economic Categories (BEC)
BEC categories are arranged, as far as practicable, to align with the System of National Accounts’ three basic classes; namely capital goods, intermediate goods and consumption goods. Commodities in BEC 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.
Trend estimates – merchandise trade
For any series, the survey estimates can be broken down into three components: trend, seasonal and irregular. While seasonally adjusted series have had the seasonal component removed, the trend series have had both the seasonal and the irregular components removed. Trend estimates reveal the underlying direction of movement in a series and are likely to indicate turning points more accurately than are seasonally adjusted estimates.
Trend estimates towards the end of the series incorporate new data as they become available and can therefore change as more observations are added to the series. Revisions can be particularly large if an observation is treated as an outlier in one quarter, but is found to be part of the underlying trend as further observations are added to the series. Typically, only the estimates for the most recent quarter will be subject to substantial revisions.
Seasonally adjusted estimates – merchandise trade volume and value series
The X-12-ARIMA package has been used to produce the seasonally adjusted and trend estimates. Seasonal adjustment aims to eliminate the impact of regular seasonal events (such as lambing, harvesting, etc) on time series. This makes the data for adjacent quarters more comparable.
The most recent seasonally adjusted figures are subject to revision each quarter. This enables the seasonal component to be better estimated and removed from the series. The largest revisions will occur in the quarter prior to the current quarter.
When statistics are released
Provisional quarterly and annual price, volume and terms of trade indexes are available within 10 weeks of the end of the reference quarter. Final indexes are released within 24 weeks of the end of the reference quarter.
Only final data are released for the services indexes. This data is available at the same time as the provisional merchandise trade indexes.
The indexes have been published in two separate releases from the September 2001 quarter. The price indexes are published in the Hot Off The Press Overseas Trade Indexes (Prices) and the volume and value series are published in the Hot Off The Press Overseas Trade Indexes (Volumes).
Further information
Responsibility for the price indexes moved from the International Trade Section/International Accounts Division to the Inflation Measures Division from 2002. The International Trade Section continue to produce the volume indexes.
A wide range of index series are available on INFOS, Statistics New Zealand's publicly accessible on-line database, or can be provided in other media, on request. There are currently 57 export and 55 import public index groupings. There are five export and five import service index groupings available on INFOS.
There are also related quarterly and annual dollar-value series available for each of the merchandise trade indexes.
General Information on Overseas Merchandise Trade Indexes
Customs documentation is the main source for the Overseas Merchandise Trade Indexes. Prices collect from the Commodity Price Survey and International Price Indexes are also used to supplement Customs Data in the calculation of Overseas Merchandise Trade Indexes. (See Source of Information - merchandise trade (above) for more details)
Commodity Price Survey - collects prices for the Overseas Services Trade Indexes.
Output Variables
Output variables are pieces of individual information that can be extracted from the survey/output data. Often output variables can be cross tabulated with other output variables, for example sales by industry classification. The list below contains all current and past output variables which have been released for this survey/output.
| Variable Name | Description |
| |
| Overseas Merchandise Trade Indexes | The following indexes are available as price, volume and value indexes for quarterly and annual periods. |
| |
| Export Series | |
| AA | Beef and Veal |
| AB | Lamb |
| AC | Lamb, Hogget and Mutton |
| AD | Other Meat |
| AE | Total Meat |
| AF | Crustaceans and Molluscs |
| AG | Fish (Live Fish, Fresh, Chilled and Frozen) |
| AH | Fish and Fish Preparations |
| AI | Skimmed and Buttermilk Powder |
| AJ | Whole Milk Powder |
| AK | Milk Powder |
| AL | Milk and Cream |
| AM | Butter |
| AN | Cheese |
| AO | Dairy Products |
| AP | Casein |
| AQ | Dairy and Casein Products |
| AR | Vegetables (Fresh and Prepared) |
| AS | Apples (Fresh) |
| AT | Kiwifruit |
| AU | Fruit (Fresh and Prepared) |
| AV | Fruit and Vegetables (Fresh and Prepared) |
| AW | Alcoholic Beverages |
| AX | Crude Animal and Vegetable Materials |
| AY | Animal Oils and Fats |
| AZ | Petroleum and Petroleum Products |
| BA | Mineral Fuels, Oils and Related Products |
| BB | Chemicals and Related Products |
| BC | Hides, Skins and Furskins - Raw |
| BD | Leather and Tanned or Dressed Skins |
| BE | Wood |
| BF | Wood Pulp |
| BG | Wood Manufacture |
| BH | Newsprint |
| BI | Paper and Paper Products |
| BJ | Forestry Products |
| BK | Wool |
| BL | Textile Yarn, Fabrics and Related Products |
| BM | Textiles, Clothing and Footwear |
| BN | Iron and Steel |
| BO | Aluminium |
| BP | Machinery and Transport Equipment |
| BQ | Food and Beverages |
| BR | Meat, Wool and By-products |
| BS | All Pastoral and Dairy Products |
| BT | Non-fuel Crude Materials |
| BU | Non-food Manufactured Goods |
| BV | Major Trading Partners - News Zealand's Total Exports to Australia |
| BW | Major Trading Partners - New Zealand's Total Exports to Japan |
| BX | Major Trading Partners - New Zealand's Total Exports to United Kingdom |
| BY | Major Trading Partners - New Zealand's Total Exports to USA |
| E9 | Total Exports |
| |
| Import Series | |
| |
| I9 | Total Imports |
| LA | Fruit and Vegetables |
| LB | Coffee, Tea, Spices and Cocoa |
| LC | Cereals and Cereal Preparations |
| LD | Sugar and Sugar Preparations |
| LE | Alcoholic Beverages |
| LF | Food and Beverages |
| LG | Alumina |
| LH | Crude Fertilisers and Minerals |
| LI | Fertilisers - Manufactured |
| LJ | Fertilisers - Crude and Manufactured |
| LK | Crude Oil |
| LL | Petroleum and Petroleum Products |
| LM | Organic Chemicals |
| LN | Chemicals |
| LO | Plastics and Plastic Articles |
| LP | Chemicals and Related Products |
| LQ | Rubber and Rubber Products |
| LR | Paper and Paper Products |
| LS | Textile Yarn, Fabrics and Related Products |
| LT | Textile Yarn, Textile Fibres, and Related Products |
| LU | Clothing and Footwear |
| LV | Textiles, Clothing and Footwear |
| LW | Iron and Steel |
| LX | Non-ferrous Metals |
| LY | Non-electrical Machinery |
| LZ | Electrical Machinery and Apparatus |
| MA | Machinery and Electrical Machinery |
| MB | Passenger Motor Cars |
| MC | Road Vehicles |
| MD | Transport Equipment |
| ME | Machinery and Transport Equipment |
| MF | Non-fuel Crude Material |
| MG | Non-food Manufactured Goods |
| MH | Total Imports, Less Fuels |
| MI | Major Trading Partners - New Zealand's Total Imports from Australia |
| MJ | Major Trading Partners - New Zealand's Total Imports from Japan |
| MK | Major Trading Partners - New Zealand's Total Imports from United Kingdom |
| ML | Major Trading Partners - New Zealand's Total Imports from USA |
| PA | Broad Economic Category 41: Capital Goods (except Transport Equipment) |
| PB | Broad Economic Category 521: Transport Equipment, Industrial |
| PC | Total Capital Goods |
| PD | Broad Economic Category 111: Food and Beverages mainly for Industry - Primary |
| PE | Broad Economic Category 121: Food and Beverages mainly for Industry - Processed |
| PG | Broad Economic Category 21: Industrial Supplies n.e.s. - Primary |
| PH | Broad Economic Category 22: Industrial Supplies n.e.s. - Processed |
| PJ | Broad Economic Category 31: Fuels and Lubricants - Primary |
| PK | Broad Economic Category 322: Fuels and Lubricants - Processed (other than Motor Spirit) |
| PN | Broad Economic Category 53: Parts and Accessories of Transport Equipment |
| PO | Parts and Accessories of Capital Goods and Transport Equipment |
| PP | Total Intermediate Goods |
| PQ | Broad Economic Category 112: Food and Beverages Mainly for Household Consumption - Primary |
| PR | Broad Economic Category 122: Food and Beverages Mainly for Household Consumption - Processed |
| PU | Broad Economic Category 61: Consumer Goods n.e.s. - Durable |
| PV | Broad Economic Category 62: Consumer Goods n.e.s. - Semi-durable |
| PW | Broad Economic Category 63: Consumer Goods n.e.s. - Non-durable |
| PY | Total Consumption Goods |
| PZ | Broad Economic Category 51: Passenger Motor Cars |
| QA | Broad Economic Category 321: Motor Spirit |
| Overseas Services Trade Indexes | The following indexes are available as price indexes for quarterly periods. |
| Export series | |
| |
| EA9 | Transportation |
| EB9 | Travel |
| EC9 | Other Services |
| ED9 | Government Services |
| E99 | Total Exports |
| |
| Import series | |
| |
| IA9 | Transportation |
| IB9 | Travel |
| IC9 | Other Services |
| ID9 | Government Services |
| I99 | Total Imports |
| |
Changes in Output Variables over time
Guide to Interpreting Data
Summary of Changes to Survey/Output ..Summary of Changes to Survey/Output ..
1915 - Export price index numbers made a first semi-official appearance in an article in the 1915 Yearbook.
1920 - An official export series going back to 1890 appeared in "Prices 1891-1919."
1924 - The Export Price Index was revised. Monthly and annual indexes used the Paasche formula on a 1909-13 (=1000) base (i.e. the weights used, related to values in the current period). The 25 commodities covered accounted for approximately 95 percent of total exports by value.
1933 - The Export Price Index was modified because an uneven collapse of prices in 1932 caused fluctuations. The weight allotted to each item included in the modified series, was the average quantity of that item exported during the previous five export seasons (i.e. years ended June). An Import Price Index, which included 220 items covering about 75 percent of the total value of imports, was produced. In the heterogeneous groups (e.g. drapery) a few specific items, for which import prices could be obtained, were regarded as representing price movements in the groups. The index was on a base of 1926 (=100) and was compiled annually on an All Groups basis (Laspeyres).
1942 - A revised Import Price Index based on, and using, the commodity weighting pattern of the three years 1936-38, and worked back to 1926, was constructed. Of the 240 items used in the calculations, about 10 percent were not import unit-values, but unit-values of other countries' (mostly United Kingdom) exports to New Zealand, or wholesale price quotations. Class weights were used to impute, to the unpriced items in a class, the same price movement of the priced items. This index was continued until 1949.
1950 - In 1949 a new and greatly enlarged commodity classification was adopted for New Zealand trade statistics, and this led to the construction of a new Import Price Index, which was calculated quarterly as well as annually. For 1950 and subsequent years, an annual index was obtained on base: the previous year, as the geometric mean of two indexes calculated respectively by using the weighting patterns of the two years (i.e. previous and current) being compared. Each annual index was then linked to that for the previous year. Thus, the index was of the chain-linked Fisher Ideal type.
1953 - The expression base of the December year 1953 (=100) was adopted for the Overseas Terms of Trade Index. The series was previously expressed on a 1936-38 base of 100.
1955 - The Standard International Trade Classification (SITC) was adopted for the presentation of New Zealand trade statistics, from the beginning of 1955. The number of export items priced was 60, which accounted for 95.4 percent of the total value of exports of New Zealand produce (other than wool), in the base period. Information for wool came from the Wool Price Index, which was based on auction prices. The new expression base was the December year 1952 (=100). The new series of export price index numbers were calculated for all periods from the first quarter of 1950, including the year ended June 1950. To obtain long-term comparisons, the old and new series were linked for the various groups, with links made through the December year 1950 and the year ended June 1950. The linked series were calculated back to the year 1914.
1959 - The Overseas Terms of Trade Index series was rebased in each of the years 1953 to 1958, with the latest year's index set to 100. In 1959, the fixed expression base of the December year 1957 (=100), was adopted. This expression base was retained until 1989.
1961 - Exports - With the introduction of a new weighting pattern, the December year 1960 (=1000) was adopted as the standard expression base for the long-term series. The series on the 1952 base, to which the older series on the 1909-1913 base had already been linked, were converted to the new base.
Imports - A new series on base: December year 1959 (=1000), commenced. It was decided to continue the method used to calculate the annual index, but the quarterly index was calculated using the weighting pattern of the previous year only, and then linked on to the index for that year. A major change was that from 1959, the price index was designed to reflect changes in the true c.i.f. cost of imports.
1971 - Export and Import Price and Volume Indexes were revised, with the chain-linked Fisher Ideal Index calculation methodology also adopted for exports. The June year 1971 (=1000) expression base was adopted for both exports and imports. Wool data, as recorded on export documentation, replaced data derived from the Department's Wool Price Index. As from the September 1971 quarter, the Overseas Terms of Trade Index was calculated as the ratio of the two Fisher Ideal indexes of export and import prices. The expression base remained the December year 1957 (=100). The choice of base was arbitrarily made at the time it was adopted and was not intended to indicate that 1957 was a normal or standard year. It was considered desirable to retain the customary expression base to avoid confusion in the use of this key series.
1982 - A revised method of computer processing of the External Trade Price and Volume Indexes commenced with the September 1982 quarter indexes, following a review of the methods used in calculating the indexes. The basic methodology of chain-linked Fisher Ideal indexes was retained, but improvements were effected in timeliness of release and the statistical quality of the indexes. The expression base of the price and volume indexes was changed to the June year 1982 (=1000), although the Overseas Terms of Trade Index remained on the December year 1957 (=100) base. The range of available indexes was also extended.
1988 - The External Trade Price and Volume Indexes were renamed the Overseas Trade Price and Volume Indexes.
1989 - The Harmonised System (HS) for classifying overseas trade was introduced on 1 January 1988, replacing the separate export and import SITC Revision 2 classifications. Comprehensive links between the old classifications and the HS were established to ensure the continuity of the published trade index series during the March 1988 quarter to June 1989 quarter changeover period. Calculation of the Overseas Trade Price and Volume Indexes directly from data in the 10 digit HS format, commenced with the September 1989 quarter indexes.
The range of published index series was revised. Some series were discontinued and some introduced, others were partially respecified to more closely reflect the commodity groupings of the HS classification, or to better reflect New Zealand's major export and import commodity groupings.
The expression base of the price and volume indexes was changed to the year ended June 1989 (=1000). The expression base of the quarterly and annual Overseas Terms of Trade Index series was also changed, from December year 1957 (=100) to base: the average of the ten years ended June 1989 (=1000).
1992 - A range of import indexes by Broad Economic Categories (BEC), which group commodities by main end-use, and also aggregate to the three main categories of capital goods, intermediate goods and consumption goods, was released on INFOS and added to the Hot Off The Press release. Some series commence with September 1982 quarter and June 1982 annual indexes, some with September 1989 quarter and June 1989 annual indexes.
For each export price and volume index grouping, related quarterly and annual f.o.b. dollar-value series were made available on INFOS. For each import index grouping, related c.i.f. value series were released on INFOS. Quarterly series commence with September 1989 quarter dollar values, June annual series with June 1990 year values, December annual series with December 1990 year values, and March annual series with March 1991 year values.
1998 - The merchandise export indexes and values were revised from September 1997 quarter to the December 1998 quarter. The merchandise import indexes and values were revised for the June 1998 quarter and the September 1998 quarter, to include updated data.
- 1999 - The Overseas Services Trade Indexes were added to the suite of Overseas Trade Indexes. The indexes use a building block structure and aggregate to the four published import and export categories as well as total imports and exports of services. A terms of trade for services is also calculated. The series' commence from the June 1997 quarter with an expression base of the June 1997 quarter (=1000). The series' are available on INFOS and added to the Hot Off The Press release.
- efforts by the New Zealand Customs Service to improve the export documentation completed by exporters
- a parallel export quality assessment by Statistics New Zealand
- a downward revision to butter export values to correct previously overvalued prices that included the tariff into the United Kingdom
- further editing of prices used in index calculations
- re-linking to more accurate annual indexes for the year ended June 1998.
- The Fisher Ideal index formula is retained.
- The price reference period and linking period are now the June quarter of each year (previously they were the June year).
- An annual weight reference period has been adopted for the Paasche component of the index (this was previously quarterly).
- Expenditure weights are being assigned at a lower level (the 10-digit Harmonised System (HS) item by country level; previously these were assigned at the 10-digit HS item level).
- Imports valued on a New Zealand dollar value for duty (vfd) basis are now being used (previously the indexes used cost, insurance and freight (cif))
- Unit values derived from administrative dollar value and quantity data collected by the New Zealand Customs Service have been selectively supplemented with prices collected directly from importers and exporters and by international price indexes.
- For existing index categories, the originally published and redeveloped indexes have been linked at the June 2002 quarter, to provide continuous long-term time series.
- All index time series have been re-expressed on a base of the June 2002 quarter (=1000). The June 2003 provisional quarter was the last quarter calculated using the old methodology, providing a one-year overlap with the new series.
2002 - Responsibility for the production of the price and volume indexes was separated. The Inflation Measures Division became responsible for the price indexes, while responsibility for the volume indexes remained with the International Accounts Division.
The merchandise export price and volume indexes and values were revised from the September 1997 quarter to the September 2001 quarter. The revised data reflects:
2003 - The Overseas Trade Indexes were redeveloped in 2003, as a result of a project started in 1999. The
redeveloped series were first released in December 2003. The main outcomes of the redevelopment are;
They enable analysts and policy makers to assess the effects of export and import price and volume level changes on the economy and on the balance of payments. Changes in export and import price and volume levels can be monitored and underlying trends analysed for forecasting the prospects of various sectors of the economy.
Underlying trends cannot be reliably deduced only from changes in the New Zealand dollar values of exports and imports. For example, rising export values due to increases in price levels produce a different outlook for the economy than do rising values due to volume increases. Changes in the value of goods exported or imported by New Zealand are the combined result of changes in prices and changes in volumes. The overseas merchandise trade price and volume Indexes provide a measure of the extent to which changes in the values of merchandise exports and imports are due to changes in price levels and the extent to which value changes are accounted for by volume changes. For example, the value of the export Dairy Products index grouping increased 10.7 percent from $1.864 billion in the June 1989 year to $2.063 billion in the June 1990 year. This was the result of a 16.4 percent increase in prices being partly offset by a 5.0 percent decline in volumes.
The export and import price indexes can be used to assess the impact of changes in export and import price levels on domestic price levels, as they can indicate possible future inflationary trends. However, merchandise import v.f.d. values exclude insurance, freight and duty, as well as costs associated with middlemen (e.g. wholesalers and retailers) and further processing; all of which may affect final retail prices.
In conjunction with changes in the nominal exchange rate, the export and import price indexes can be used to monitor changes and trends in world prices.
Export and import price indexes are also used in escalation clauses in export and import related contracts.
Within Statistics New Zealand, export and import indexes are used to calculate Expenditure on Gross Domestic Product (GDP) at Constant Prices, and Indexes of GDP at Constant Prices by Production Group. Selected price index series are used to deflate current export and import values, and some volume index series are used to extrapolate base period values. In addition to the use of various published export and import index series this way, a range of index series is produced specifically for this purpose.
While the overseas trade indexes are not used directly in the preparation of Balance of Payments statistics, they are used by staff for analytical purposes.
Non Response Bias
The overseas services trade indexes are based on prices collected from respondents. Where there is no response for a particular period, the price is imputed. In most cases, the price is imputed by taking the most recently available price and carrying it forward. This means the index shows a bias toward no change. Should a respondent not respond for several periods, a bias occurs towards no change.
Limitations of Overseas Merchandise Trade Index Data
The unit-value approach used in calculating overseas merchandise trade price and volume indexes has some limitations. Where there is a mix of goods exported or imported under an HS item code, and the mix differs from quarter to quarter, this change in mix can have an effect on the derived unit-value. In general, HS item descriptions are reasonably precise and goods classified under particular codes are sufficiently homogeneous for any change in mix to be unlikely to have a significant effect on item unit-values. However, in some areas such as machinery imports and exports, chemical imports and textile imports, many items do display variable unit-value behaviour, due to the inclusion of commodities that are not sufficiently homogeneous. In these areas, relatively fewer items are considered reliable enough to be used as explicit price indicators. Unreliable items are not explicitly priced, and have imputed to them, price movements of reliable items of similar type.
In other areas, such as pharmaceutical products, HS items do not have statistical units of quantity. Unit-values cannot be calculated for such items and they are also imputed.
With the introduction of the re-developed series of the Overseas Trade Indexes in December 2003, the areas that display variable unit value behaviour and the areas where unit values cannot be calculated, are selectively supplemented with prices directly collected from importers and exporters and by International Price Indexes.
In general, though, the unit-value approach is considered to be satisfactory, and to provide a good measure of changes in export and import price and volume levels.
When the New Zealand HS Classification was prepared by the Customs Department, Statistics NZ had significant input at the detailed level. With a view to maintaining and improving the quality of the Overseas Trade Indexes, Statistics NZ requested more detailed item splits and specific units of quantity, where necessary.
Related Data Sources ..Overseas Trade Statistics, Balance of Payments Statistics
Sampling Errors ..Sampling errors do not apply to the overseas merchandise trade indexes.
The overseas services trade indexes are based on a purposive sample of commodities, selected to reflect the price changes for the particular service measured. Due to the sampling methodology sample errors can not be calculated.
Non-sampling errors Non-sampling errors in the overseas merchandise trade indexes data may result from incorrect data being entered upon Customs entries and mistakes being made during the editing of the data.
Non-sampling errors in the overseas services trade indexes data may result from respondent error on the Commodity Price Survey, mistakes made during processing survey results and non-response imputation. Statistics NZ adopts procedures to detect and minimise these types of errors but they may still occur and are not quantifiable.
Caveats on Release ..
Catalogue & Reference Numbers
- Prices:
Overseas Trade Price And Terms Of Trade Indexes
Merchandise Export Price Indexes
Merchandise Import Price Indexes
Merchandise Imports By Broad Economic Categories - Price Indexes
Overseas Trade in Services Price Indexes
Volumes:
Overseas Merchandise Trade Seasonally Adjusted Volumes and Values
Merchandise Export Volume Indexes and Values
Seasonally Adjusted Merchandise Export Volume Indexes
Seasonally Adjusted Merchandise Export Values
Merchandise Import Volume Indexes and Values
Seasonally Adjusted Merchandise Import Volume Indexes
Seasonally Adjusted Merchandise Import Values
Merchandise Imports By Broad Economic Category - Volume Indexes
Seasonally Adjusted Merchandise Imports By Broad Economic Categories - Volume Indexes
Other Comments
Classification(s) used
Glossary of Terms
| Term | Description |
| 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, including insurance and freight. A value which represents the cost to the importer of purchasing the goods and the insurance and freight to bring the goods wharfside in New Zealand. It excludes any duty paid on the goods. |
| Consumption Goods | Goods used (without further transformation in industrial production processes) by households, government or non-profit institutions serving households. - durables have an expected usage of three years or more, eg. appliances, furniture. -semi-durables have an expected usage of one or two years, eg linen,shoes, toys. -non-durables have an expected usage of less than a year, eg. soap, yarns books. |
| Fisher Ideal | The Overseas Trade Price and Volume Index series are of the chain-linked Fisher Ideal type. |
| |
| FOB | Free On Board. Valuation for exports. The value of the goods at the moment they leave NZ. |
| Government services (exports) | Includes the estimated expenditure of foreign embassies in New Zealand, the portion of the New Zealand government's international aid spent in New Zealand, and the government's receipts from immigration fees and passport and visa sales. |
| Government services (imports) | The operational expenses of New Zealand's embassies overseas, and the costs of New Zealand defence forces stationed overseas. |
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| HS | Harmonised System, the 10-digit harmonised commodity classification. |
| Imports | Goods which add to the stock of material resources in NZ as a result of their movement into the country. |
| Intermediate goods | Goods used up or transformed in industrial production processes. |
| Laspeyres Index | The Laspeyres index is a base-weighted index and uses the previous June year's values as weights. |
| Merchandise trade | Exports or imports of goods which increase or decrease the stock of material resources in New Zealand. Includes goods leased for a year or more. |
| NZ Produce (Exports) | All goods and materials grown, produced or manufactured in NZ and articles wholly or partly manufactured in NZ from imported materials which have changed in character as a result of the production process. |
| Other services | Services other than transportation, travel and government services. Examples are insurance, royalties and licence fees, banking and financial services, computer and information services, telecommunications, and personal cultural and recreational services. |
| Paasche Index | The Paasche index is a current-weighted index and uses the current quarter's values as weights. |
| Provisional Data | Index data will remain in a provisional state (i.e. subject to updating) until they are finalised some four months later. |
| |
| Re-exports | Exported goods which were earlier imported into New Zealand and which include less than 50 percent New Zealand content by value. |
| Transportation | The international carriage of goods and passengers. Includes freight, air fares, port services, and stevedoring. |
| Travel (exports) | The expenditure of overseas visitors while travelling in New Zealand, and the expenditure by international students in New Zealand. |
| Travel (imports) | The expenditure of New Zealanders while travelling overseas. |
Contact Details
| Customer Service E-mail Contact: | info@stats.govt.nz |
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| Survey Enquiries E-mail Contact: | sun.kim@stats.govt.nz |
Liability
Statistics New Zealand gives no warranty that the information or data supplied contains no errors. However, all care and diligence has been used in processing, analysing and extracting the information. Statistics New Zealand shall not be liable for any loss or damage suffered by the customer consequent upon the use directly, or indirectly, of the information supplied in this product.