Additionally, to account for the hierarchical structure of the data, municipalities (Terrassa, Sant Boi de Llobregat, Molins de Rei, and Gavà) will be added to the model as random effects factors.
This meant information available in the official web sites of the "KOSTRA-data" (Municipality-State-Report) in Norway, the Swedish National Board of Health and Welfare ("Socialstyrelsen") and Oral Health Register (the SCOR system, National Board of Health) in Denmark.
Figure 1 illustrates the national health registers which in Norway was the "KOSTRA-data" (Municipality-State-Report), in Sweden the Swedish National Board of Health and Welfare ("Socialstyrelsen"), and in Denmark the Oral Health Register ("the SCOR system" ("Sundhetsstyrelsen Centrale Odontologiske Register"), National Board of Health)).
This exclusion is due to the lack of data a municipality level regarding the quality of forests.
The EBB contains a variable called 'RIN' that stands for the personal identification number which allows researchers to combine it with various datasets such as the tax data and municipality registrations by using this id.
Aggregation of data on municipality level makes interpretation of the results at the individual level difficult.
The age and sex distribution of participants in the survey was compared with Census 2001 data for municipality of Salamis [ 11].
Detailed population data on municipality level is only available from census that takes place in Switzerland every 10 years with the last one taking place in 2010.
Data on municipality characteristics were obtained from the Portuguese National Statistics Institute (INE), providing information on the 2008 population, number of nurses, number of hospital beds, proportion of foreigners applying for residency in the municipality, and on 2007 purchasing power per capita.
Up-to-date census data per municipality are published each year by Statistics Sweden [ 25] and historic records on population (for the time of the Russian and the Asian Influenza) have been collected and made available to researchers at the Demographic Data Base [ 26] at Umeå University.
