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Accuracy and reliability

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Personal Finance and Welfare, Social Statistics
Uwe Pedersen
+45 39 17 34 24

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Indices of Average Earnings for the Private Sector (Discontinued)

The accuracy and reliability is mainly affected by two factors. First of all, the index is based on a sample, which in itself cause some uncertainty. Second of all, there is some uncertainty connected to the completeness in the collected data, which is often caused by errors in the way the system is generated for transmission of data. An example of this is a payroll system where the different wage compositions are not correctly linked or reported, and thus give an inaccurate picture of the development of wages. The problem with errors like these is that they tend to be difficult to discover. For example would reporting of a low and wrong value for irregular payments result in too high calculation of wage developments, as the irregular payments could not be separated from the wage component.

Overall accuracy

The overall reliability of the index is considered to be reasonably high. This is based on the fact that the number of enterprises in the sample should be sufficient and that the coarse search for errors before the production process make sure to sort out observations with errors. This is especially true for the total value of the index and for the largest branches of economic activity. However, for the smallest branches of economic activity the accuracy are lower.

Sampling error

Not available at the current moment.

Non-sampling error

Other uncertainties are primarily linked to mistakes in enterprises reporting of components for the wages of their employees. This could for example concern components like irregular payments, e.g. bonuses and delayed regulations of wages. When these are not correctly registered in the payroll system of the enterprise, they can have unintentional consequences for the calculations of wages. As such, the problem is not not caused by non-response, but rather errors present in the enterprises payroll systems, which can be quite difficult for the enterprises to detect. At the same time it is not always possible to detect the errors during the coarse search for errors before the production process, as it is not necessarily given that there should be payments of this kind in a given period.

Quality management

Statistics Denmark follows the recommendations on organisation and management of quality given in the Code of Practice for European Statistics (CoP) and the implementation guidelines given in the Quality Assurance Framework of the European Statistical System (QAF). A Working Group on Quality and a central quality assurance function have been established to continuously carry through control of products and processes.

Quality assurance

Statistics Denmark follows the principles in the Code of Practice for European Statistics (CoP) and uses the Quality Assurance Framework of the European Statistical System (QAF) for the implementation of the principles. This involves continuous decentralized and central control of products and processes based on documentation following international standards. The central quality assurance function reports to the Working Group on Quality. Reports include suggestions for improvement that are assessed, decided and subsequently implemented.

Quality assessment

An overall assessment of quality is not available. Still. the sample is drawn in a way to ensure that a high share of the employees in the statistical population actually are present in the sample of companies and organisations with at least 10 persons employed. At the same time should the search for errors performed on the data make sure that both the total measured development in wage and the development in wage for the largest branches of economic activity show reasonable and robust results. For these reasons, the quality of the index is considered to be quite good.

Data revision - policy

Statistics Denmark revises published figures in accordance with the Revision Policy for Statistics Denmark. The common procedures and principles of the Revision Policy are for some statistics supplemented by a specific revision practice.

Data revision practice

Only final figures are published. for the index not seasonal adjusted. For the seasonal adjusted index revisions are made from time to time.