What does the survey comprise?
A description of employment, pay and working hours of employees.
All jobs of employees in the Netherlands, in practice all jobs that fall under the Dutch wage tax legislation. Jobs of Dutch people working abroad are excluded, jobs of foreigners working in the Netherlands are included. There are no restrictions based on age or weekly working hours. Jobs of self-employed workers are excluded.
Job. Because each job belongs to a person and to a company, jobs can be classified by personal and corporate characteristics.
Date/year survey started
In 2006 the SWL replaced the employment and wages survey (EWL). Before 2006 data were collected by surveying companies; now wage declarations to the tax authority are used as the source of the data. For the period 1995 to 2005 data on employment, pay and working hours of workers are available from the EWL, the predecessor of the SWL.
Figures for 2009 are definite; figures for 2010 are provisional. New figures for 2011 will be published in December 2012, these will be definite.
How is the survey conducted?
Registration. The main source of the data is the register with information on wages and social contributions of the organisation responsible for the implementation of social insurance and benefits (UWV).
Companies with salaried staff periodically usually every month or every four weeks, declare salaries paid to the tax authority. The tax authority collects wage tax and employee insurance premiums from each company. Statistics Netherlands receives complete company level information about the rating principles and associated charges and premiums from the tax authority.
The tax authority provides information about the remuneration per job to the UWV, which uses this information to construct a register with information on wages and social contributions. This register contains information on the employment history of all registered employees. These data are delivered completely by the UWV to Statistics Netherlands.
UWV and the tax authority.
There is no sample, the statistics are based on the complete registration. The register information on wages and social contributions contains the entire target population. In 2009 the population comprised over 500 thousand companies with a total of approximately 7.9 million jobs.
Control and correction methods
Internal consistency and completeness of the register with information on wages and social contributions is checked. Changes from previous years are also checked for plausibility. If necessary data are adjusted. Missing data are estimated and internal consistency of the different variables is also checked.
Quality of the results
The introduction of salary declarations on 1 January 2006 was initially accompanied by large problems with respect to each of the quality criteria: timeliness, completeness and accuracy. Because of this the results were delayed and the quality of the data for 2006 and 2007 was lower than intended. This was especially noticeable in results at the level of and changes in small sub-populations. From 2008 onwards the quality has improved.
Data are comparable over time with regard to definitions and methods. The values of variable properties, such as age, company size and economic activity are not fixed.
Statistics Netherlands is working closely with the UWV and the tax authority to increase the quality of the data further. The strategy is to improve the quality of wage declarations as much as possible, so that as little correction as possible is needed. Statistics Netherlands monitors the quality by assessing the plausibility of time series of a large number of aggregates, and frequently of individual data of companies or jobs.