External trade in goods

Imports and exports
Imports comprise mainly foreign manufactured goods entering Norway. This can also include re-importation of originally Norwegian-produced goods and processed goods. Exports comprise domestically produced goods sent out of Norway, i.e. the Norwegian statistical territory as defined in Section of population. Also included are reexportation of originally foreign-produced goods and processed goods.

Trade in goods is based on the physical movement of goods across borders, but for some items, such as ships, oil platforms and aircraft, trading often takes place without the occurrence of such movement. Whether there has been an import or export of such goods is therefore determined based on whether a change in economic ownership has taken place cf. also described in the Section of population. Economic ownership is defined as the person entitled to claim the economic benefit and who has the legal responsibility for the risk of the item.

Mainland exports
As from March 2013, the statistics on external trade in goods will use the term mainland exports on the exportation of goods other than crude oil, natural gas, natural gas condensates, ships and oil platforms. Previously, we also used the term traditional goods for these exports, as well as for imports excluding ships and oil platforms. (Balance of payments and the research department still use the term traditional goods. The balance of payments also includes items such as naphtha, propane and butane in its collective term crude oil and natural gas, external trade in goods does not.)

Goods

A good is a physical object. Trade in goods, both relate to and are bound by trade in services. Services are more intangible by nature than goods. Production and consumption of goods is often independent of each other, while a service is difficult to distinguish in the same manner. Sometimes it is difficult to determine whether an object is a commodity or a service, e.g. software. Software may be defined as a service even if it is stored in a physical product and production and consumption take place independently. The content, i.e. the developed software, is mostly a service.

Country
Country of origin is used for imports. With regard to exports, the country of destination is used.

For raw materials, the country of origin is determined according to where the goods are produced. For manufactured goods (processed and refined goods), this is the country in which the goods have obtained the form they have at the time of import. The country of destination is defined as the country, which, on the date of export, is the last known country for which the goods are intended.

For more specific principles in relation to country of origin, the rule for ships, aircraft and oil platforms is that country of origin is the country that previously owned the goods (economic ownership). For Norwegian-produced goods sold abroad and subsequently bought in Norway, the country from which the goods are imported shall be given as the country of origin (manufacturing country).

Mode of transport
Mode of transport is defined as the means of transportation used when goods cross the border, either by import or export (in the Database for Standard Classifications there is a detailed description of mode of transport ).

Quantity
For most goods, the quantity is expressed in kilograms (weight excluding packaging), except for ships and electricity, which are measured by gross tonnes and kWh respectively. However, for many goods, the quantity is also available in a different unit of measurement, such as pieces, barrels, cubic metres, carat, litres, pairs etc.

Statistical value
Statistical value is the value when crossing the Norwegian border. Duties, VAT and other taxes are not included in the statistical value.

Upon import, the value should be set to the CIF (Cost Insurance Freight) value, i.e. the value of the goods at the Norwegian border, including the costs associated with the delivery of goods to the border, transport costs and insurance. Similarly, for exports it is the value at the Norwegian border, including the costs associated with transporting it there, called FOB (Free On Board) value. CIF and FOB are two types of delivery terms called Incoterms. The delivery terms are an agreement between buyer and seller as to who bears the risk, responsibility and cost of transportation of the goods to the agreed place. In the Database for Standard Classifications there is an overview of the different delivery terms .

For crude oil exported by ship directly from installations on the Norwegian continental shelf, the value upon departure from the installation is used. In the case of crude oil and natural gas that is piped abroad, this value is determined based onon when it leaves the Norwegian continental shelf. The value of transport in international waters and into a terminal abroad is regarded as export of services.

The statistical value of exports and imports of ships is the transfer value including takeover of debt. With regard toto fish landed abroad (exported) by Norwegian vessels and caught outside the Norwegian customs border, the statistical value is the value of the fish paid to the fishing operator upon the sale of stock (minus the sales organisation fee).

County of production
The county of production is defined as the county in which the added value is greatest.

Classification of goods
The classification by HS (the international customs and statistics nomenclature, the Harmonized System) is a 6-digit grouping of goods organised primarily according to the material characteristics of goods at the time of crossing the border. Only in exceptional cases is the later use of the goods of any significance to the classification. The WCO (World Customs Organization) is responsible for this nomenclature.

The Norwegian customs tariff is based on the HS, but has two more digits, which are national codes. The 7th digit reflects national customs divisions/tariff rates (bound in the WTO - World Trade Organization). The 8th digit is used to cover the national statistical needs and and among others the interests of the Norwegian Agricultural Authority and Ministry of Foreign Affairs interests with regard to import and export regulations. In some cases, the 8th digit is also used to distinguish between goods subject to duties and/or fees. The Norwegian version is published annually on our website along with a text version of the nomenclature developed by Statistics Norway. The detailed commodity list , which includes all commodity numbers, also provides information about the validity of each commodity number.

Due to technological developments and changes in international trade, the HS nomenclature is normally updated every 5 years – with the most recent implementation on 1 January 2012. In addition, minor changes are made in the Norwegian customs tariff every year. The EU also uses the nomenclature of the HS in its publication of foreign trade figures. However, the EU version; the Combined Nomenclature (CN) - which also has eight digits - is more detailed than the Norwegian version. As mentioned previously, only the first 6 digits are common internationally.

When publishing external trade figures, the UN Standard International Trade Classification (SITC) is mainly used. Here the goods are grouped by level of processing (raw materials, semi-finished and finished goods). As from 1988 to 2006, the SITC-Rev.3 is used, but as of 2007 the SITC-Rev. 4 is used.

The classification BEC (Broad Economic Categories); the UN classification of commodities by end use, which is based on the SITC, is also used to some extent. This classification is not considered to be a "standard classification" in the same way as for example the SITC, and it is officially acknowledged that countries may have their own version of this grouping in order to satisfy national needs. In the Database for Standard Classifications the Norwegian version of this classification is found.

The various nomenclatures are listed on the UN’s website , as well as correspondence tables between the different nomenclatures HS, SITC and BEC and their different versions.

The product classification CPA divides goods by industry group, and in external trade we use extracts from this. CPA (Statistical Classification of Productivity by Activity in the European Community) is the EU's central Product by Activity classification. It is a product group that is closely linked to industry, i.e. distinctive products within each activity can be linked to the activity classification NACE Rev.2.

Grouping by country
The Norwegian list of countries used follows the international standard ISO-3166. EU countries use the same standard, except for some deviations of less importance.

In the external trade publications these country groupings are frequently used:

Nordic countries - trade with Sweden, Denmark, Greenland, Faroe Islands, Finland, Åland and Iceland
EFTA - trade with Iceland, Switzerland and Liechtenstein
EU – in the Database for standard classifications current member states at any given time is available
OECD - for current member states at any given time see the OECD's website

Developing countries – as from 2007, the figures are according to the OECD’s DAC (DAC stands for Development Assistance Committee) for definitions of countries at any given time that are recognised as recipients of official foreign aid. The DAC list also includes a section on LDCs (Least Developed Countries - defined by the UN) - which we also use in the statistics.
(Until 2006, these countries were defined as developing countries in the Norwegian trade statistics: Bosnia-Herzegovina, Yugoslavia (Serbia and Montenegro), Croatia, Macedonia, Malta, Slovenia - Africa except South Africa - Asia excluding Japan, North and South America except USA, Canada and Greenland - Oceania except Australia and New Zealand.)

Former Comecon (only European Comecon countries in the Norwegian trade statistics): Armenia, Azerbaijan, Bulgaria, Estonia, Georgia, Belarus, Kazakhstan, Kyrgyzstan, Latvia, Lithuania, Moldova, Poland, Romania, Russia, Slovakia, Czech Republic, Tajikistan, Turkmenistan, Ukraine, Hungary, Uzbekistan.

Statistics on imports and exports of goods are published at country level. Export figures are also given by county of production.

Monthly figures are released on the 15th of the month after the observation period (the previous month), or the first subsequent working day.  With every new release, all the previous monthly figures are updated in every publication.

For more information about Revisions, please see Accuracy and Reliability.

Reports are sent to the EU statistical office (Eurostat), Organization for Economic Cooperation and Development (OECD), World Trade Organization (WTO), International Monetary Fund (IMF) and the United Nations (UN).

Non-revised and revised micro data are stored in accordance with Statistics Norway's guidelines for storing computer files (DataDok).

The purpose of the external trade statistics is to provide information about the commodity flows between Norway and other countries. Exports and imports are important economic indicators both in describing structural changes and in monitoring the economic trends. The monthly statistics of external trade in goods have been published since 1913 (value figures were published for the first time in 1866).

With regard to essential changes in the statistics, the commodity classification in line with the Harmonised System that was introduced in 1988 entailed a comprehensive restructuring of the distribution at a detailed level in relation to the earlier CCCN nomenclature (the Customs Cooperation Council Nomenclature).

The statistics are mainly financed from State assignments, but also rely to some extent on market income.

The external trade statistics are a part of the national and international statistical system, and are used in the compilation of the national accounts and the balance of payment statistics in Statistics Norway. The statistics are aimed at covering the business sector’s need for data in this area for their planning of production, marketing and sales.

The statistics are also intended for prognoses and analyses performed by public authorities, research institutions and private organisations. International organisations such as the UN´s statistical office, the Organization for Economic Cooperation and Development (OECD),  the statistical office of the EU (Eurostat) and others make use of the information provided in the external trade statistics.

No external users have access to the statistics and analyses before they are published and accessible simultaneously for all users on ssb.no at 8 am. Prior to this, a minimum of three months' advance notice is given in the Statistics Release Calendar. This is one of Statistics Norway’s key principles for ensuring that all users are treated equally.

The figures for external trade statistics are an important part of the quarterly balance of payments and national accounts and the annual national accounts .

Operational accounts (balance of payments comprises operating accounts and capital accounts), however, include several items on both the export and import side that are not included in the statistics on external trade. This applies to the export and import of services in their entirety. External trade statistics only cover the non-financial sector, while the balance of payments cover all institutional sectors (the non-financial sector produces goods and non-financial services, while financial firms are mainly concerned with financial disclosure and financial assistance services).

The balance of payments also collects estimates of trade in goods which are transported directly from abroad to the Norwegian continental shelf, imports of fuel and other oil products to Norwegian ships, aircraft and units abroad. Moreover the external account interprets some of the goods from the external trade statistics in goods as a service, such as computer games, software and licenses.

In the publication of the figures for external trade we give figures for crude oil, natural gas and condensates, while the balance of payments use the collective term “crude oil and natural gas”. Terms in foreign accounts also encompass items such as naphtha, propane and butane, while the external trade statistics do not.

In addition to the statistics mentioned, external trade figures are included in many of the other statistics published by Statistics Norway, for example:

- Exports of salmon ,  weekly figures of salmon exports are published in addition to the regular monthly trade figures
- Indices of volume and price of external trade in goods mainly use external trade data as the basis for calculating figures. In addition, the total number of imports and exports, as well as fish and some selected commodity numbers for waste paper and scrap metal, are used as basic data in the producer price index  and the  price index of first-hand domestic sales
- External trade data are also used as basic data for statistics on transport  , the external trade in ICT goods ,  statistics on fishery and emissions of greenhouse gases

Mirror statistics
Mirror statistics, in the context of external trade statistics, refer to a comparison between the statistics of two or more countries: exports of goods from one country should in principle equal the imports of the same goods in the partner country.

However, discrepancies are often identified in these figures for several reasons. Although there are international guidelines for the production of external trade statistics, there may still be differences in what the countries include. An example is differences in the usage of statistical trade systems, general or special trade, which causes delimitations to the statistics content. Countries may also have different methods for data collecting and processing, which can create distortions. Furthermore, some countries collect data from customs authorities and others directly from companies. 

Basically, there should be a certain difference in value between the countries, as the exporting country provides the FOB-value while the importing country in addition to this adds costs for insurance and freight all the way to the location of delivery, the CIF-value (see Definitions). Some countries collect data from customs authorities, others directly from companies. A common source of error between countries is caused by different information about which is the country of destination. Different threshold-values for inclusion of data can also create distortions, f.ex. in Norwegian external trade statistics, declarations with value less than NOK 1 000 are excluded from the import statistics. Other countries may have other delimitations. Different practise of confidentiality and demands for confidentiality, inaccurate definitions of certain commodities as well as conscious and unconscious misuse of codes can lead to use of different classification codes between countries.

From a Norwegian point of view, there is a need for comparing external trade data with the corresponding statistics of our main trading partners, principally European countries. It is in this context important to have knowledge of the rules practiced by the individual partners.

The Statistical Office of the European Union, Eurostat, publishes external trade data for EU countries, totally for the Union and separate for each member country. This statistics are produced according to EU regulations, which defines external trade as trade between the European Union trade and third countries. As a consequence of this, exports to countries in the EU from a non EU-member state are recorded as imported to EU in the first country where the goods cross the borders of the European Union. When forwarding the goods to the country of destination, the good is recorded as an item dispatched from the EU-country that first received the goods. Information about the country of origin of the commodity is not included in the records. Several of the EU-countries publishes in addition to the data presented in the Eurostat database, Comext ,  separately external trade statistics produced after national methodology. For information about this, consult Eurostat's annual report: Quality report on International trade statistics .

The Statistics Act §§ 2-1, 2-2 and 3-2

EU regulations incorporated into the EEA agreement comprise contractual obligations pursuant toto EC regulations onon data collection and distribution of data to the EU’s statistical office, Eurostat. The current regulations are as follows:

Regulation (EC) No. 471/2009 of the European Parliament and of the Council of 6 May 2009 on Community statistics relating to external trade with non-member countries and repealing of Council Regulation (EC) No 1172/95

Commission Regulation (EU) No. 92/2010 of 2 February 2010 implementing Regulation (EC) No. 471/2009 of the European Parliament and of the Council on Community statistics relating to external trade with non-member countries, as regards data exchange between customs authorities and national statistical authorities, compilation of statistics and quality assessment

Commission Regulation (EU) No. 113/2010 of 9 February 2010 implementing Regulation (EC) No. 471/2009 of the European Parliament and of the Council on Community statistics relating to external trade with non-member countries, as regards trade coverage, definition of the data, compilation of statistics on trade by business characteristics and by invoicing currency, and specific goods or movements

Commission Regulation (EU) No. 1106/2012 of 27 November 2012 implementing Regulation (EC) No. 471/2009 of the European Parliament and of the Council on Community statistics relating to external trade with non-member countries, as regards the update of the nomenclature of countries and territories

Statistics area and the economic territory
The scope of foreign trade statistics is based on international guidelines from the United Nations Statistical Commission.

The general recommendation is that the statistics should include all goods which add to or subtract from the stock of material resources of a country by entering (imports) or leaving (exports) its economic territory. In addition to the geographical dimension, a country's economic territory also includes ships, aircraft and oil platforms owned by national corporations. These are goods that are not necessarily located within the geographic area, but are still viewed as part of the material resources of a country. For these goods external trade is measured by the change of economic ownership.

There are two different statistical trade systems - the general trade system and the special trade system. UN recommends using the general trade system where a country's statistical area coincides with its economic territory. This implies that goods are recorded at the time they enter or leave the economic territory. The special trade system is used when the statistical area covers only a part of the economic territory. Statistics Norway follows, with a few exceptions, the general trade system.

The Norwegian economic territory consists of mainland Norway, Svalbard, Jan Mayen, Norwegian dependencies, territorial waters, including the airspace above these, the economic zone, the Norwegian part of the continental shelf, territorial enclaves abroad (embassies, consulates, military bases, research stations) and Norwegian ships, aircraft and oil platforms.

External trade statistics is mainly based on information drawn from customs declarations. However, the responsible area of the customs authorities only covers mainland Norway and its territorial waters. As a supplement, data on important trade in goods to and from the remaining areas of the economic territory are collected directly from respondents and registers.

The following are defined as statistical area:

Mainland Norway and its territorial waters
Customs declarations contain information on physical flows of goods crossing the customs border. Imports and export that are exempted from ordinary declaration are referred to in the Customs Act §§ 4-10 and 4-11. According to the recommendations from the UN, some flows of goods should be excluded from the statistics. This includes trade in Norwegian goods between the customs area and other parts of the Norwegian economic territory. To the extent possible, trade in foreign goods to and from foreign enclaves, ships, aircraft and oil platforms located in Norway are omitted. To distinguish this type of transactions customs procedure codes from the declarations are used. In general, trade transactions are recorded at the time when the goods enter or leave the customs territory. However there are some exceptions, cf. the treatment of goods in customs warehouses.

There are four different types of customs warehouses. Goods waiting on declearance,can be stored in either a general or a central warehouse. For imports the time of recording is set when the goods are taken out of the warehouse and not when they arrived in the economic territory. This means that the statistical processing of these data follows the special trade principle. However, in practice the time difference between storage and withdrawals from warehouses is usually so small that the statistical processing is considered to be approximately equal to the general trade principle. For the remaining two types of customs warehouse; duty free and storage for further processing, the statistical treatment is according to the general trade system.

Customs declarations of exports and imports of electric current do not provide enough information for statistical purposes, and data is therefore obtained directly from the respondent.

Svalbard and Jan Mayen
Import transported through the Norwegian mainland to Svalbard and Jan Mayen should be declared by customs. Data on exports of coal transported directly from Svalbard are collected directly from the respondents.

The Norwegian part of the continental shelf
Imports via the Norwegian mainland to Norwegian owned installations and vessels that operate on the continental shelf should be declared by customs. Exports of crude oil and natural gas delivered directly from the continental shelf are based on data from the Norwegian Petroleum Directorate and the different operators.

Norwegian owned ships, aircraft and oil platforms
Exports and imports of ships, aircraft and oil platforms are based on information from Norwegian ship registers as well as from different respondents. Export of Norwegian goods (excluding bunkers) to foreign ships and aircraft in Norwegian ports and airports are covered by customs declarations.

Data on exports of fish caught by Norwegian fishing vessels outside the customs area and landed abroad is obtained from the Directorate of Fisheries.

In accordance with the UN recommendations the following trade in goods are not included in the statistics:

• Goods in transit, ie goods attending the Norwegian economic territory to be directly transported to a recipient outside this area
•  Goods traded through intermediate trade, ie goods transported between two foreign countries without entering the Norwegian economic territory
• Goods physically crossing the country border, but defined as a service (including newspaper subscriptions, accompanied baggage, household goods)
• Content delivered electronically (including e-books, downloadable games, etc.), defined purely as a service
• Issued banknotes, securities and monetary gold
• Samples, gifts and promotional material etc. with a low value
•  Goods for repair or return after repair
•  Goods in unaltered condition in return to vendor (claims etc.) and waste containers, replacement deliveries and free repairs (warranty)
•  Items for temporary use, that are returned within 12 months (exhibition, demonstration, scientific research, loan, professional equipment, transport vehicles in international traffic, containers, equipment in use for the press, radio and television equipment, etc.)
•  Change in ownership of non-financial assets
•  Goods that are damaged on the journey to and from the Norwegian economic territory
•  Satellites equipment moved to and launched in other countries without any change of ownership
•  Goods functioning as means of transport (ship, aircraft, packaging, etc.)
• Waste and scrap without any commercial value

 Furthermore goods totalling less than NOK 1 000 are omitted, these goods amounts to less than one per cent of the import and about 0.04 per cent of the export. Imports of goods for less than NOK 200 and exports of goods less than NOK 5.000 (except from goods that are subject to taxes and restrictions) are not subject to declaration by the Customs.

The statistics are mainly based on administrative information obtained from TVINN, which is the Norwegian Customs’ electronic information system for the exchange of customs declarations between businesses and Norwegian Customs. Some data is, however, obtained from other sources, and more information on this can be found in the paragraph on data collection.

Sampling is not not relevant as external trade is a total count of the goods defined in the population.

Data collection

The vast majority of the data is, as mentioned, collected through the Customs’ TVINN register and transmitted electronically to Statistics Norway. However, some additional data, as shown below, is obtained separately.

Exports of crude oil and natural gas in gaseous state
Preliminary and final figures for exported volumes of crude oil and natural gas in gaseous state are collected through monthly reports from the operators and the Norwegian Petroleum Directorate. The prices, however, are obtained via various sources depending on whether they relate to crude oil or natural gas, and whether the data is being collected to compile preliminary or final figures.

From 2013 on, the development in the in gas prices from the producer price index (PPI) used to calculate the preliminary gas prices for foreign trade, while the level will be based on the value determined from the last registered price. PPI obtain figures for natural gas from the journal World Gas Intelligence (WGI).

Preliminary oil prices are based on the reference price of  Brent Blend for the current month.

For crude oil, the final prices: quarterly surveys from the licensees, as well as information from the Norwegian Petroleum Directorate, the Ministry of Petroleum and Energy and the operators.

For natural gas, final prices: a quarterly average price based on information from a selection of licensees and operators.

Due to insufficient information about country of destination there are from 2013 on changes in the dissemination of the figures of exports of natural gas in gaseous state. From 2013, country of destination according to these figures will be based on the landing point of the pipelines with natural gas from the Norwegian continental shelf.

Imports and exports of ships and oil platforms
The data collection for vessels is based on current information from the Norwegian ship registers the Norwegian Ordinary Ship Register (NOR) and the Norwegian International Ship Register (NIS).

When it comes to oil platforms, information is collected from the Norwegian ship registers, the Customs’ TVINN register and importer/exporter.

Imports and exports of electricity
From 2016 information is collected from Customs' TVINN register. In previous years this information was received from the Nordic Power Exchange Nord Pool.

Imports and exports of aircraft
For some aircrafts, monthly reports are received from Statistics Sweden, while the rest are obtained through regular declarations in the TVINN system.

Exports of coal from Svalbard
Reports on the export of coal from Svalbard are received monthly from the exporter. 

Exports of fish caught by Norwegian vessels outside the Norwegian customs border
Since July 2010, the figures have been obtained from the Directorate of Fisheries (FDIR). Prior to that, the information was gathered through TVINN.

Data editing

Information from customs declarations is subject to statistical controls in the Customs declaration system (TVINN). The controls to check the estimated price, quantity and country were developed by the Customs in cooperation with Statistics Norway.

Data controls at Statistics Norway take place at different levels - some as soon as the data is loaded into the system (automatic recoding of variables). The manual part of the revision consists of different types of validity and probability tests. The former are controls of absolute errors, such as missing transport code, while the other type of test may check unlikely country codes or unreasonably high quantities for a specific type of good. The system aims to intercept the most serious errors in the data. Data collected from sources other than the Customs also undergo similar checks.

Estimations

External trade is based on a total count but some items are excluded, cf. section of population. There is no need for any statistical estimations of current figures, only aggregations, in order to enable us to publish in a timely manner.

 The seasonal adjustment method, which is used for the foreign trade monthly value series and the quarterly volume series, consists of pre-treatment of the values for the individual series using the seasonal adjustment programme X12-ARIMA. It was developed by the US Bureau of the Census, and is one of the most internationally known methods for seasonal adjustment. The purpose of the seasonally-adjusted figures is to show the real economic trends by eliminating interference caused by seasonal variations. There are two important corrections: one method adjusts for the number of weekdays of different kinds in each month. This can be important, since it is probable that exports and imports are distributed unevenly throughout the week. The second important correction is for the Easter holidays, since Easter can fall in different months and different quarters of the year. We assume that both imports and exports are affected the week before Easter, in the Easter week itself and the week after Easter. No special corrections are made for other holidays in the year.

The Statistics Act § 2-6 covers the disclosure of information. The requirements for confidentiality in external trade of goods are practised so that data is suppressed only when the establishment/enterprise has a valid reason for confidential treatment and actively asks for it. This is called "passive confidentiality" and is in line with UN recommendations. This method is used by most countries. Exporters/importers can demand suppression when there are 3 or fewer companies that import or export an item type, or when a company has a market share of over 90 per cent, or if two firms have a market share of over 95 per cent.

Since Norway has a number of major manufacturers that are dominant in some product areas, some suppression of information exists on the export side. Between 5 and 10 per cent of mainland exports are affected by confidentiality. For imports, it is far less; around 1 per cent. Some commodity areas are more problematic with regard to dissemination, since suppression on highly aggregated levels must be carried out.

The six-digit HS-based commodity classification is subject to revisions due to technological development and also development in the commodity spectres of the international trade. These adjustments are normally made every five years. The most recent HS revision was implemented on 1 January 2012. Furthermore, national adjustments are made every year at the national eight-digit level. These revisions can create breaks in the time series for some commodity numbers. Detailed information about this is available in the yearly Commodity List External Trade. Correspondence tables between the different editions of the HS are available on the UN website .

With regard to the divisions according to the SITC, the current SITC-Rev.4 was introduced in January 2007, when it replaced the previous SITC-Rev.3 (1988-2006). The relation between the figures for the years before and after 2007 can be misleading for some commodity numbers. The degree of influence depends on the value of the commodity numbers that now have a different group affiliation. Correspondence tables between the different editions of the SITC are also available on the UN website .

For the tables that use the CPA nomenclature, the 2008 edition is used for the whole series.

Other elements influencing the comparability over time: The imports and exports of ships and oil platforms in the statistics were extended in 1991 to include transactions that concern vessels under a foreign flag with a Norwegian-registered holding company. Furthermore, the definition of developing countries was changed in 2007, which affects the figures slightly.

Collection errors can occur from incorrect values, incomplete information or misinterpretation of data on customs declarations. Examples of this are use of wrong commodity number, country code, county of production or incorrect quantity.

Other sources of error include late updates, which sometimes occur for the trade with ships and oil platforms.It is also difficult to intercept the transit trade, i.e. the buying and selling of commodities in foreign territory where a Norwegian company is one of the partners. Neither do we have a good data basis to estimate the processing exports for the preparation of goods abroad or imports for processing in Norway.
The rules for customs clearance, which entail exemption from the duty to declare for exports of goods when the value is below NOK 5 000 and exemption for imports of goods when the value is below NOK 200, lead to lower figures than the real trade. This is not the best solution for preparation of the national accounts, where these lacking figures are estimated separately.
The calculation of seasonally-adjusted data beyond the usual seasonal effects is adjusted for the fact that trade is distributed unevenly across the week and taking into account the effect of Easter, as described in the section of estimations. However, beyond this nothing in particular is done. Therefore it would be natural to assume that the seasonally-adjusted December figures should be interpreted more cautiously because of the Christmas holidays.

The export trade statistics is a full count, so there are therefore no non-response errors or sampling errors .

When publishing statistics for a new month of measurement, figures for the previous months in the same year are also revised. Furthermore, the figures for all months of the year are revised twice more: First time in May the following year (year t + 1), before final figures are published in May one year later (year t + 2). See https://www.ssb.no/en/statbank/list/muh in the Statbank for more information about the size of the revisions.

At the aggregate level, the difference between preliminary monthly figures and revised figures published in May year t + 1 will normally be small for imports and mainland exports. At a detailed level and for individual months, the revisions can be of greater importance, relatively speaking. For oil and gas, larger audits can be experienced, in particular, related to the calculation of oil and gas prices. The revisions of the final publication in year t + 2 will normally be of minor importance, but in some cases relatively significant corrections can also be uncovered in this time perspective.