Maritime transport
What does the survey entail?
Purpose
To compile information on cargo transport between seaports located in the Netherlands and seaports abroad, whereby cargo is either loaded or unloaded outside the Netherlands. Occasionally, the transport of domestic goods is included in maritime transport, such as cargo that is transported between two different Dutch seaports via international waters.
The data is broken down by the direction of transport (inbound and outbound), type of goods/sea container, partner country and seaport in the Netherlands.
Target population
All goods handled in seaports in the Netherlands that have arrived or departed in seagoing vessels and for which Dutch customs has registered clearance. This includes transport to and from the Dutch continental shelf. Transport within a port area is excluded.
Statistical unit
Goods that are loaded or unloaded from seagoing vessels in seaports in the Netherlands and go through official customs procedures.
Start of survey
The survey in its current form began in 2021. Figures based on older methods are available from 1996 onwards.
Frequency
Raw data is delivered on a monthly and quarterly basis. Core figures are updated on a quarterly basis, while detailed information is compiled only once a year based on complete annual figures.
Publication strategy
Figures on maritime transport are available on a quarterly and annual basis. Core variables are published quarterly. Detailed information is published in its final form every year. The quarterly figures for the current year are provisional. Provisional quarterly figures become available five months after the reporting period.
How is the survey conducted?
Survey type
The survey is based on integrated data collection from all registered inbound and outbound vessels at seaports in the Netherlands that go through official customs procedures.
Data collection method
Statistics on maritime transport are largely based on secondary data collected from several data sources. The main data source for the transshipment of goods arriving by sea is the Customs Administration of the Netherlands. The figures on ship movements form the backbone of the statistics. Data on incoming goods is registered by Dutch customs in the Import Control System (ICS); data on outgoing goods is registered in the Export Control System (ECS). Statistics Netherlands (CBS) receives specific selections from these systems on a monthly basis.
The data provided by Dutch customs includes information about the cargo, such as which overseas ports the goods are loaded/unloaded at, the weight transported and a description of the goods. The Netherlands’ main seaports – Rotterdam, Amsterdam, North Sea Port and Groningen Seaports – provide data on incoming and outgoing vessels and their cargo.
Compared to the figures from the port authorities, the Export Control System produces a substantial underestimate of outbound transport (by about 30 percent). Data sources provided by Dutch customs lack the detailed data on the transport of goods (and passengers) by ferry. This information is retrieved directly from the ferry operators. The publication figures are based on data provided by Dutch customs, port companies and ferry services.
Data suppliers
Dutch customs, port authorities and ferry operators.
Sample size
Integrated data collection of all vessels loading or unloading at seaports in the Netherlands.
Checking and correction methods
Statistics Netherlands (CBS) mainly checks the plausibility of the raw data. Plausibility checks are made by comparing and, where necessary, supplementing customs information with data from companies. Here, the focus is mainly on the extent to which the figures for the weights and quantities of the goods loaded and unloaded are complete.
Weighting
Not applicable.
Quality of the results
Accuracy
-
Sequential comparability
Maritime transport data has been compiled and processed in the current survey structure since 2021.
Quality strategy
Prior to publication, the results of statistical surveys are checked for plausibility. To verify the plausibility of the results, Statistics Netherlands carries out the following checks:
- Internal consistency checks (the ratio between variables and sources)
- Comparisons with results from other sources
- Time series analyses (consistency over time)