Price rise for freight transport by road

Definitions

Name and topic: Name: Freight transport by road, price index
Topic: Prices and price indices

Responsible division: Transport, Tourism and ICT Statistics

Definitions of the main concepts and variables: The price measured in this index is invoiced price on transportation services, exclusive VAT. The turnover used to weight the index is collected in the structural business statistics and is defined as the sum of remuneration for rendering services to customers, sales of merchandise and gross income from other activities. Rental income and commissions are included, while special taxes, public grants and profit on the disposal of fixed assets are not. VAT is not included in the statistics.

Standard classifications: The index is made up by different sub-indices based on freight types. The sub-indices are: Frozen or refrigerated goods, petroleum products, other liquids or gases in bulk, mixed goods/container goods, dry goods in bulk and other transportation in special vehicle.

Production

Population: The population is all businesses in Norway classified as 60.24 (Freight transport by road), SIC2002. The statistical unit in the survey is local kind-of-activity units.

Data sources and sampling

Statistic Norway's Business Register and Vehicle register are used to draw the sample. Figures on the unit's turnover are collected in the structural business statistics.

The sample is approx. 150 local kind-of-activity units.

Collection of data, editing and estimations

The survey is based on a quarterly postal questionnaire combined with information from the Business register. The questionnaire is posted by the end of each quarter with a three weeks deadline. Respondents that haven't returned the questionnaires by the deadline are given a postal reminder together with a one-week extension of the deadline. If the questionnaire still isn't returned the respondent is given a fine and a one-week final extension of the deadline.

The questionnaire is read optically and controlled and revised both automatically and manually. If price changes seem unlikely large the respondents are contacted.

For each unit in the sample, price change per freight type is calculated. The next step is to calculate sub-indices for each freight type, and finally a main index where all the sub-indices are included in the calculations. The sub-indices are weighted together in the main index using the industry turnover distributed on freight types as weights. The units are classified into three different strata on the basis of unit turnover. The index is calculated as Laspeyres Index with fixed weights. The weights will be fixed for a period of approx 5 years.

Confidentiality: The use of collected data from respondents will be in accordance with the demands made by the Data Inspectorate. The information will be stored properly and kept confidential.

Comparability over time and space: The time series started in the 4th quarter of 2004. There have not been changes in the calculation method.

Accuracy and reliability

Sources of error and uncertainty

Errors might be caused by questionnaires that are not correctly answered. There are two main sources to measurement errors. One is that the respondent states the same price even though there has been actual price change between two quarters. The other is that the respondent gives prices on another delivery than he is supposed to do. If a measurement error is suspected, the respondent is contacted to get the right price. Data is also controlled when the questionnaires are optically read. In general, the production system ensures that the data is controlled on both detailed and aggregated level.

Non-response will always be a factor in form-based surveys. This is because some respondents do not return their forms or forms are rejected because they are incompletely filled out. About 97 per cent of the questionnaires are returned to Statistics Norway.

The sample of 200 units constitutes approx. 2 per cent of the industry's population. Because of the fact that the population in the industry is homogenous and that the sample is stratified, the sample is considered to be large enough. Even though the sample is drawn based on the freight types the units are most likely to transport, the units are not instructed to report prices on specific freight types. Thus, there is a chance that some of the freight types are better represented in the sample than others. It has not been made any calculations regarding sampling errors.

The weights are collected in the structural business statistics from 2004. Thus, a source of error could be outdated weights. The reason of why the weights are not collected every year is that the industry is stable and it will take time before changes will result in a new industry structure.

Model error may result in insignificant price changes. For every index number standard errors are calculated. Freight types with few observations are more likely to be insignificant.

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Freight transport by road, price index, Q2 2008

About the statistics

Definitions

Administrative information

Background

Production

Accuracy and reliability

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Freight transport by road, price index, Q2 2008

Content

About the statistics

Definitions

Administrative information

Background

Production

Accuracy and reliability