Notes on methodology in 2013 – 2014 period, Methodological explanations

European cities face a variety of challenges, ranging from population ageing, through migration and urban sprawl, to counteracting climate change. By contrast, Europe's dynamic cities attract investment, people and services, thereby stimulating creativity and innovation. Cities are seen as both the source and solution of economic, environmental and social challenges. Therefore, cities are central to achieve the Europe 2020 targets and these are: smart, sustainable and inclusive growth.
Statistics on urban and rural areas measure economic, social and environmental issues and provide information for a range of different analyses, for example, to study which areas have: the highest risk of unemployment; the highest proportion of their respective populations aged 65 and above; or the highest concentration of employment within a particular activity.

Areas and regions can be categorised according to the degree of urbanisation. Based on population size and density, they indicate if an area or region is a:
1. rural area (thinly populated area)
2. town or suburb (intermediate density area)
3. city or urban area (densely populated area).

Different data from various administrative and statistical sources were used. In most cases, it was necessary to select a data source that would be most acceptable for subnational statistics. Most often, the data of the Croatian Bureau of Statistics were used.

Data sources were the following:
  • Data collected from the Croatian Bureau of Statistics
  • Data collected in cities
  • Data collected from others (state and private organisations).

Selected cities were Zagreb, Rijeka, Slavonski Brod, Osijek and Split. Zagreb, the capital city, has a population of more than 250 000 inhabitants, while population of other cities ranges between 50 000 and 250 000 inhabitants. All cities together cover approximately 25% of the national population.

In order to determine the state of data for 2013 and 2014, it was necessary to estimate data coming from censuses. It should be noted that the territorial system of the Republic of Croatia (counties, cities and municipalities as well as spatial units within cities) has remained unchanged since 2001 Census. Therefore, the estimation could be done as follows:

The population data for 2001 and 2011 were compared for all units of territorial system in order to determine the linear trend and the factor of the monthly increase or decrease. The data with the situation as of 1 January 2013 and 1 January 2014 were obtained by extrapolating the 2011 Census data in a way that the 2011 Census data were multiplied by a factor of the monthly increase or decrease for 21 months (to provide the situation as of 1 January 2013) or 33 months (to provide the situation as of 1 January 2014). During that process, the structure that existed in the 2011 Census  was used, actually the distribution of data on sex, age and other ranges, because it is generally assumed that nothing can significantly change in one or two years.

Various additional estimating methods were used as well. For example, if the length of bicycle network in one city becomes longer, it is assumed that percentage of commuting by bicycle is also higher. Some data have been estimated according to information from real estate agencies (such as average price for a dwelling, average price for a house and average annual rent for housing per m2).

It should be noted that there were some deviations from the actual definitions. For example, the municipality of Okrug has been included as a part of the Split larger urban zone, although it does not share a land border with other parts of the larger urban zone. However, the municipality of Okrug is located on an island and shares a sea border with other parts of the larger urban zone.

Concerning economic activity, a work-based definition of job was used and data were collected from the Statistical Business Register instead from the employment and wages statistics and the Labour Force Survey.
Larger urban zones around selected cities were selected as follows: it was determined for every city if the commuting rate was over 15% (according to the 2011 Census data) within municipalities and towns at the LAU 2 level and continuous larger urban zones (no holes or gaps) were created. The only exception was the Split larger urban zone, which included the municipality of Okrug although it shares no common land border with other components of the larger urban zone. Since the municipality of Okrug is located on an island, it shares a sea border with other components of the larger urban zone.

Larger urban zones (LUZ) were created by the Croatian Bureau of Statistics only for the needs of subnational statistics on the basis of the nearest neighbourhood criterion. Such a delimitation of areas is suitable for these needs, since there are more than 500 towns and municipalities in the Republic of Croatia, which are a good basis for the construction of a homogenous quite appropriate elements for the construction of a homogenous larger urban zone.

Number of sub-city district (SCD) units ranges between 9 and 22. The number of population for identified units varies between 3 992 and 70 009 inhabitants (per There were more than 5 000 inhabitants in three sub-city districts according to the 2001 Census, but less than 5 000 inhabitants according to the 2011 Census.

The Croatian data for variables “number of dwellings connected to potable drinking water supply system” and “number of dwellings connected to sewerage treatment system” are in fact data on the state of being connected to potable drinking water supply system and sewerage treatment system. It is impossible to estimate a number of connected households in the Republic of Croatia, since more than one of them (in some cases even hundreds of dwellings) use the same connection to the water supply system. The situation is similar in most European countries, which caused the urban audit statistics methodology to be changed and now definitions refer to population connected to potable drinking water supply system and population connected to sewerage treatment system.

Notice: The project on subnational statistics was carried out in cooperation with Eurostat.

All data published on the webpages of the Croatian Bureau of Statistics were approved by Eurostat and they are available on  http://ec.europa.eu/eurostat/web/cities/data/database?p_p_id=NavTreeportletprod_WAR_NavTreeportletprod_INSTANCE_KhPDfq283AOB&p_p_lifecycle=0&p_p_state=normal&p_p_mode=view&p_p_col_id=column-2&p_p_col_count=1