SANFL Boundary Analysis
Background
The South Australian National Football League (SANFL) approached Professor Graeme Hugo in early 1996 with the problem of re-designing the club boundaries to reflect changes in the age structure of the population. The SANFL consists of nine clubs that are allocated areas of Metropolitan Adelaide and Country South Australia from which they can recruit and develop junior football talent.The clubs are primarily interested in the junior football talent (aged 0 to 19 years) within each of their allocated zones. To foster and develop the game, and to identify potential league footballers, most clubs actively participate in school football programs and conduct junior coaching clinics.
In recent years, the age structure of the population in many of these allocated areas has changed dramatically. As a result, there is a wide discrepancy in the number of males aged 0 to 19 within the existing club boundaries.
Methodology
The numbers of males were obtained from data collected at the 1991 ABS census of population and housing. The 5 year lag between the census collection date and the time of the analysis effectively meant that the number of males aged 0-19 reflects the current male population aged 5-24. Data from the 1996 census will be available around mid 1997. For visualization, the census data was mapped by Census Collection District (CCD) for metropolitan Adelaide. The same process was used for the the country areas.
To determine the number of young males within each club boundary the existing club boundaries were intersected with the census boundaries. As a result of the intersection procedure, each CD was now attached to a particular club. In cases were a CD area was intersected by a club boundary the population was allocated to the appropriate club based on the population density of the whole CD.
Interpolated Male Popn. = Proportion of CD * Population Density
The new boundaries were derived by re-allocating CD's to clubs in an attempt to equalize the numbers of young males within each club boundary. The data analysis and mapping was performed using ARC/INFO version 7.0.
Results
Adelaide Metropolitan Area
The difference in the number of young males aged 0 to 24 for each club ranged from 26000 to 15500. The clubs with highest numbers of young males are located in young high growth areas north and south of the city, whilst the clubs with the lowest numbers were mainly situated in the inner metropolitan areas. The map below shows the number of young males by CCD for metropolitan Adelaide. The map clearly shows the higher numbers of young males in the CD's away from the inner metropolitan areas.
The re-distribution of CD areas to form new club boundaries results in a less than 10 percent discrepancy between the number of potential males for each club. The map below shows the old and new club boundaries.
Country South Australia
For many league clubs the country regions provide a large number of young footballers. Hence each club is allocated a section of the state in which they can scout for local talent.
In the past each club has been allocated a number of Local Government Areas that make up their country recruiting zone. A criticism of the old method was that in some cases a local football league was divided by a SANFL recruiting zone, hence players in the same league were touted by different SANFL clubs. To overcome this problem the separate country league catchments have been considered when re-allocating the Local Government Areas. The map below indicates the proposed country recruiting zones.
Other Developments
The new boundary proposal was presented and implemented by the SANFL in November 1996. Since then further work has been carried out by Simon Ronald using Genetic Algorithms to optimize the club boundaries.
Other work has been carried out mapping the membership databases for the Adelaide Crows, Port Adelaide and Football Park. The data has been mapped by postcode area.