The Brazilian Institute of Geography and Statistics releases this Monday the publication Regions of Influence of Cities: Methodology of hierarchical compatibility between the editions of the survey in the period from 1966 to 2018. The historical context and the methodology adopted throughout the five editions of the survey Regions of Influence of Cities (REGIC) will be released. From then on, the direct comparisons between the editions will be presented in terms of assessment of the hierarchy of cities, evolution of the areas of influence, as well as the demographic evolution of urban centers.

Patterns observed over time

According to Marcelo Motta, an IBGE geographer and manager of the study, the biggest methodological changes occurred between the 2007 and 2018 editions. The change was due to the conceptual advance in understanding the urban network. In the 1966, 1978 and 1993 editions, the urban network is known only as the result of the commuting of people to obtain goods and services. In the 2007 and 2018 editions, the Theory of Central Flows is incorporated, aiming at analyzing the economic functions and the distribution of services in the geographical space through the relation with the organization of the population, as well as at explaining, ultimately, the logic of the localization of different activities in urban systems. The geographer states that the commuting of people is "half the story." The "other half" are the informational, immaterial and network management links created by urban activities.

"REGIC 2018, in particular, was the only one in which the IBGE network went directly to the municipalities to apply a questionnaire to informants. In the other editions, the survey was answered by the IBGE branches, based on their knowledge of the territory. An operational improvement was the use of DMCs (mobile data collection devices), which streamlined the survey by sending the results directly to the database, allowing to check the consistency in real time, automatically blocking data collection errors," states Marcelo Motta.

The Regions of Influence in 1978 - second edition of the study

Background of the study

Since 1996, the IBGE studies how cities influence the development of the country. REGIC is in this context as it identifies and analyzes the Brazilian urban network, establishing the hierarchy of the urban centers and their regions of influence.

REGIC has a ten-year periodicity, being 2018 the last edition. Throughout the editions, the survey assessed how cities relate to each other, by means of the commuting of people looking for goods and services. In addition, links between multi-sited public institutions and enterprises were assessed as well.

In every edition of the survey, REGIC influenced many academic works, according to interpretations on the Brazilian urban network. According to Marcelo Motta, an IBGE geographer and technician in charge of the survey, the survey serves as the basis for managing cities. He states that "public managers and enterprises might use it as the basis to take location decisions: where to open a new hospital or university, for instance, where to open a new shopping mall under the point of view of the market."

Methodology of the Study

The methodology of the survey is complex, being established by the hierarchical level of the territorial management of the cities. The measurement is made by decentralized public institutions, such as the INSS, Federal Revenue, Federal Justice, etc. It also counts the multi-sited enterprises, those that have headquarters and branches in different municipalities. "The greater the presence of these entities and organizations, the greater the capacity of a city to articulate with others and the higher the hierarchy," states Marcelo Motta.

According to the manager of the study, the hierarchy is also used in several points of the survey. One of them is the capacity of cities to provide goods and services for the population living in other centers. Another one is the link of the territory management. The link is the relation between private and public institutions, with the commuting of people to acquire goods and services. Motta mentions the example "of a resident in a municipality that does not have the good or service required, causing him to commute to a larger city to acquire it."

Some factors define the rise or fall in the hierarchy. The economic trend of that place with time is one of the reasons. It usually happens with the economic growth, making the urban network a more complex entity. The researcher mentions the example of São Paulo - the state has 20 regional capitals, which are right below metropolis.

Possible updates in the future

Scheduled to be released in 2025, the publication will update the management of the territory. The survey was improved with the incorporation of the state management, including the databases of the state health and education structures. Motta complements that, from then on, the capillarity of the public management will increase and it will emphasize the presence of the intermediate centralities in the urban network. The next REGIC - in 2028 - will take into account the federal management on top of the state one.