Content
About the statistics
Definitions
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Name and topic
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Name: Transport by vans and small lorries
Topic: Transport and tourism
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Responsible division
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Division for Energy, Environmental and Transport Statistics
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Definitions of the main concepts and variables
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Carrying capacity
Carrying capacity is the differnce between the maximum permissible weight of the vehicle and the sum of the unladen weight of the vehicle and the weight of driver (75 kg).
Total weight of the vehicle
The maximum permissible weight of the vehicle included people and goods.
Combined vehicle
Lorries or vans with an extra row of passenger seats behind the driver’ seat.
Small lorries
Lorries with a carrying capacity of less than 3.5 tonnes.
Small combined vehicles
Combined vehicles with a carrying capacity of less than 1 tonne.
Large combined vehicles
Combined vehicles with a carrying capacity of between 1 and 3.5 tonnes.
Small vans
Vans with a carrying capacity of less than 1 tonne.
Large vans
Vans with a carrying capacity of between 1 and 3.5 tonnes.
Multi-stop journeys
Laden journeys with more than one stop for loading and unloading en route.
Single-stop journeys
Laden journeys where the whole of the load is transported from one place to another.
Transport for own account
Transport of own goods on own account.
Transport for hire or reward
The carriage for remuneration of persons or goods on behalf of third parties
Commodity
Type of commodity defined according to the EU’s Standard Goods Nomenclature for Transport Statistics (NST 2007).
Vehicle-kilometres
Kilometres driven with and without load.
Vehicle-kilometres with load
Kilometres driven with load.
Tonnage carried
Gross weight of the transported goods, packaging included.
Goods transport performance
The transport work which is performed when a vehicle carries a certain amount of goods over a definite distance.
Laden journeys
Journeys with load (from unladen vehicle to unladen vehicle)
Average length of laden journeys
Average length of journey with load
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Standard classifications
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EU's Standard Goods Nomenclature for Transport Statistics (NST 2007)
Administrative information
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Regional level
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County.
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Frequency and timeliness
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Frequency: Similar surveys are intended to be carried out every five years. Timeliness: The statistics are published within six months of the end of the statistical year.
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International reporting
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Not relevant
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Microdata
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Historical data are stored as text files.
Background
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Background and purpose
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The purpose of the statistics is to describe the transport performances of Norwegian vans and small lorries. Vans and small lorries constitute a transport segment with increasing importance for the transport of goods on Norwegian roads, particularly in the cities.
The statistics on transport by vans and small lorries were established in 2009, based on a sample survey conducted in each quarter of 2008. The development of the statistics was partly financed by the Norwegian Ministry of Transport and Communications (MTC). The statistics succeed a similar survey conducted by the Norwegian Institute of Transport Economics in 2003 (ITE).
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Users and applications
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The statistics are primarily used in transport planning and transport models by public authorities and research institutes (MTC, the Norwegian Directorate of Public Roads (DPR), ITE, Statistics Norway). Transport organisations and transport companies are also main users. In Statistics Norway the figures are also included in energy and emission analysis of the Norwegian transport sector.
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Equal treatment of users
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No external users have access to the statistics and analyses before they are published and accessible simultaneously for all users on ssb.no at 08 am. Prior to this, a minimum of three months' advance notice is given inthe Statistics Release Calendar.
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Coherence with other statistics
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The statistics on transport by vans and small lorries supplement Statistics Norway's quarterly survey on road goods transport carried out by heavy lorries and road tractors (with a carrying capacity of 3.5 tonnes or more).
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Legal authority
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Statistics Act sections 2-1, 2-2, 2-3 (filing requirements)
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EEA reference
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Not relevant
Production
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Population
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The population consists of vans and small lorries which are registered in the Norwegian Register of Vehicles throughout or in parts of the statistical year. The owner of each vehicle in the survey sample is the reporting unit, while the vehicle itself is the observed unit and the statistical unit. Vans and small lorries are defined as lorries, vans and combined vehicles with a carrying capacity of less than 3.5 tonnes. Vehicles with special license plates and vehicles registered prior to 1 January 1990 are not included in the statistics.
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Data sources and sampling
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The statistics are based on a sample survey. Information about the population of the survey is collected from the Norwegian Register of Vehicles, which contains data on ownership, registration status and technical characteristics of the vehicles.
The gross sample of the survey consists of 10 000 vans and small lorries, which is sample of about 2 per cent of the 500 000 vans and small lorries which were registered in the Norwegian Register of Vehicles throughout or in parts of 2014.
The sample was selected by simple random sampling in a total of 114 strata. The vehicles where stratified by type of vehicle (3 groups) and county (19 groups) prior to sampling. The number of vehicles sampled from each vehicle type is proportional to the potential for transport performance of the vehicles in each group.
In order to ensure that a sufficient number of vehicles were selected from each county, half the number of sampled vehicles in each vehicle group was selected equally from each county. The other half was selected proportionally to the total number of vehicles in the same vehicle group in the county.
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Collection of data, editing and estimations
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The survey was conducted as an Internet survey. Owners who failed to submit a completed questionnaire within the given deadline were reminded twice by mail. The survey is subject to filing requirements for owners of vans and small lorries registered as enterprises in accordance with the Norwegian Statistics Act (1989) .
The survey was carried out during two weeks in third quarter of 2014, fourth quarter of 2014, first quarter of 2015 and second quarter of 2015. The quarterly sample of 2500 vehicles was distributed randomly between the survey weeks. Accordingly, round about 1250 owners of vans and small lorries were asked to report on their transport performances in each of the eight survey weeks of 2014 and 2014: 38, 39, 46, 47, 7, 8, 20, 21.
The returned questionnaires are checked for recording errors and other obvious errors. The submitted information is subject to both logical controls on the observation level and more macro oriented analysis focused on identifying outliers and curious observations. Partial non-response is dealt with either by removing the observation from the net sample or by estimating a value for the missing observation based on other information about the vehicle.
The data for the survey week for each vehicle is converted to yearly estimates by multiplying by 46 assumed weeks of activity during a normal year (52 weeks with 6 weeks of vacations and holidays deducted). This is the same conversion factor that was used by ITE in 2003.
The sample figures are converted to population figures by using a rate estimator. The weights used for calculating the total figures for each stratum are calculated by dividing the total vehicle-kilometres for a stratum in the population by the total vehicle-kilometres for the same stratum in the survey sample. The vehicle-kilometres for the population are collected from the statistics on distances covered by vehicles which Statistics Norway is disseminating annually from 2009.
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Seasonal adjustment
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Not relevant
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Confidentiality
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Not relevant
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Comparability over time and space
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The statistics succeed a similar survey conducted by the Norwegian Institute of Transport Economics in 2003 (ITE). Similar surveys are intended to be carried out every five years.
Accuracy and reliability
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Sources of error and uncertainty
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Measurement errors are errors that that occur during data collection and are caused by the survey instrument. Vagueness inn the questionnaire used for data collection may for instance lead to the recording of wrong values. The respondent may also consciously or unconsciously, give erroneous data or interviewers may influence the answers given by respondents. A typical error may be use of the wrong scale when answering questions.
Processing errors are errors introduced during data processing in Statistics Norway.
The logical and statistical controls are tailored to detect these types of errors in the collected data. A certain degree of respondents using wrong scales when giving information in kilometres or kilograms have been corrected in the manual checking of questionnaires that did not pass the control sequences. Apart from this, the scope of measurement errors and processing errors in the survey is unknown, but is not believed to introduce systematic errors in the results.
Non-response errors are errors caused by unit non-response, i.e. that the owner of the van or small lorry has failed to respond, or item non-response, i.e. that the owner has failed to respond to some but not all the questions in the survey.
In the survey of transport by vans and small lorries, unit non-response is mainly due to one of three circumstances: Vehicle owners who can not be reached by mail, vehicles that have been sold, discarded or out of use in the survey week and vehicle owners who do not reply when contacted. Unit non-response contributes to the skewness and an uncertainty added to the uncertainty due to sampling errors.
Item non-response occurs when the owner has failed to respond to some questions, but has given enough information to make the response useful to the survey. Two examples that occur in the survey are when the owner of the vehicle has failed to answer questions about the tonnage carried or the number of laden journeys in the survey week. In such cases, the tonnage or journeys are estimated using other information about the vehicle and type of transport.
Sampling errors arise from the fact that the estimates are based on a sample and not a census of the entire population. The sampling error is measured by the standard error which estimates the expected deviation between the survey estimate and the estimate that would have been obtained if a complete enumeration had been carried out. On average, the sampling error for all samples is zero.
For the survey of vans and small lorries the sampling errors occur on two levels: when the sample is drawn and when the specific survey week is assigned to the vehicle. Stratification before the sample is drawn has the intention of reducing the sampling error.
The coefficient of variation is a normalised measure of the sampling error. The coefficient of variation measures the standard deviation of a measurable variable as a ratio of the standard derivation of the variable to the estimated mean of the variable.
In the survey of vans and small lorries there may be coverage errors due to time gaps in registration. For vehicles that are sold, deregistered or scrapped just before or during the relevant quarter, the information in the Norwegian Register of Vehicles may not be accurate at the time of sampling. Vehicles that are wrongly selected to the sample due to such coverage errors are included in the unit non-response error.
In addition to coverage errors, there will be errors in the survey due to deficiencies in the reported activity of the vehicle in the survey week. Approximately 20 per cent of the owners report that their vehicle has not been used in the survey week. Data on the same vehicles from the statistics on distances covered by vehicles, which is based on odometer readings, suggest that the lack of use in the survey week is far from representative for the activity level of these vehicles in the statistical year as a whole. To avoid calculating too low estimates for the transport performances carried out by vans and small lorries, the vehicles that are reported to be out of use in the survey week are included in the unit non-response of the survey.
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Revision
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Not relevant