What does the survey comprise?
The monthly publication of changes in prices of consumer goods and services. The price changes are shown as an index. In the derived consumer price indices, the effect of changes in the rates of product-related taxes (for instance VAT and excise duty on alcohol and tobacco) and subsidies is eliminated. The derived CPI answers the question: how would prices have changed if the tax rates had remained the same?
Consumer goods and services purchased by Dutch households.
Consumer goods and services.
Date/year survey started
The figures in the most recent month are provisional. They become definite when the figure for the subsequent month is published.
How is the survey conducted?
The study is based on monthly price observations at companies and organisations that supply goods and services to consumers.
Although many prices are observed by interviewers in retail outlets, more and more retail chains also provide price-data sets (scanner data). Statistics Netherlands also uses written and telephone surveys, internet monitoring, external registrations and brochure/catalogue information.
The observed prices are adjusted by eliminating price effects of current taxes, and subsequently applying the tax rates of the previous December. The same is done for product subsidies.
Companies, institutions, associations and government.
Over 1,300 items and services, and 10,000 respondents (excluding scanner data).
Checking and correction methods
Statistics Netherlands checks the completeness and plausibility of the incoming data. If the data are incomplete or implausible the respondent is asked to provide more information. In the case of non-response, the data will be imputed (the necessary information is estimated based on the remaining observations). When a product or service in the survey package is changed, a correction is applied for any differences in quality between the old and the new version of the product.
To measure price changes, a package of goods and services is compiled. Each product or service in this package is assigned a weight, an indication of how important it is in the consumption pattern of Dutch consumers. The consumption expenditure of National Accounts is used to determine the weights of the various goods and services in the CPI. In addition, budget surveys and other external sources are also used. The weights of the products and services in the CPI are updated and published annually in January.
Quality of the results
The accuracy and representativeness of the CPI are guaranteed by measuring prices of a very large and diverse number of products. Each month the prices are measured at different sales channels throughout the country. However, it is impossible to calculate the degree of accuracy. The accuracy of price changes for a group of products is generally lower than that for the total consumption package. The survey response rate is over 95 percent.
Inaccuracies can arise at several stages in the production process:
• sampling respondents
• selection of representative items and estimation of quality differences
• measurement errors
• determination of weighting factors
• as a result of non-response
Where possible prices are included of products observed for the same respondent in two consecutive months. Since the publication of the series 2006=100, weights have been adjusted annually (base shifts). At that moment a new package of products and services is determined for which prices are measured. The weights in the package are also updated. The data are therefore not the same year after year, but they are comparable.
The data are checked for internal consistency and completeness. When necessary, action is taken to verify the data. If the data are correct, the price indices are calculated and the results are verified and validated. Validation is done by another department.
Taxes which are corrected for in the derived CPI (December 2010)
Value added tax (VAT)
Purchase tax on motor vehicles
Excise on beer
Excise on wine
Excise on fortified wines (e.g. port and sherry)
Excise on other alcoholic products
Excise on mineral oils
Excise on tobacco
Consumption tax on non-alcoholic beverages
Stock charge on petroleum
Tax on legal transactions: insurance premium tax
Environmental tax on tap water
Environmental tax on energy tax
Motor vehicle tax
Surface water pollution tax
Waste disposal rates (including refuse collection)
Water and sewage rates for residents
In January 2010, Statistics Netherlands introduced a new method for computing price indexes in the CPI and HICP, based on scanner data. More information can be found in the survey description:
The use of supermarket scanner data in the Dutch CPI.