EXPLORING THE NEW ABS GEOGRAPHY WITH BUILDINGS DATA


Introduction
Background
Case study #1
Case study #2
Case study #3
Case study #4
Conclusion
Further information


INTRODUCTION

From July 2011, the ABS began to release data using the Australian Statistical Geography Standard (ASGS). Regions and boundaries from the previous Australian Standard Geographical Classification (ASGC), such as Statistical Local Areas (SLAs), are being replaced by new geographies. The first ABS series released on the ASGS was Building Approvals, Australia (cat. no 8731.0) and this article uses these data in case studies to illustrate the change.


BACKGROUND

Some benefits of this recent change to the ASGS include:

• The regions at each level of the ASGS ABS structures are more consistent in population size.
• The regions at each level of the ASGS ABS structures are optimised for the statistical data to be released for them.
• The Main Structure Statistical Area (SA) units are based on the idea of a functional area and built around whole official gazetted localities, which will result in more meaningful regions.
• The regions at each level of the ASGS ABS structures will remain stable until the next Population Census in 2016.

More information on the ASGS can be found by visiting the Geography Portal on the ABS website. This includes details about the new ASGS regions referred to in this article, for example, the Statistical Area 2 (SA2) and Statistical Area 3 (SA3) regions.

The four case studies presented in this article illustrate some impacts from changing to the ASGS:

• Case Study #1 shows a former SLA (ASGC) that is now represented by eight SA2s (ASGS), with the result that more regional data is now available.

• Case Study #2 shows where five sparsely 'populated' SLAs are now one SA2.

• Case Study #3 is an example of where a Statistical Subdivision (SSD) covers an apparently similar geographic area to two SA3s. However, as the area covered by the SA3s is slightly different, understanding where the boundaries are is important. Also, in this example, the component SA2s within the SA3s offer more regional data than previously under the ASGC.

• Case Study # 4 shows another example of different boundaries. In this case, the SLA and SA2 have similar names but cover different areas.

CASE STUDY #1

Map 1A shows the SLA (ASGC) representing the City of Armadale in Western Australia.




Under the ASGS, this SLA is now represented by the SA3 of Armadale and its eight SA2s, providing a greater level of geographic detail (Map 1B).


Under the ASGC, the SLA of Armadale (C) had 708 new houses approved from July to December 2011. Under the new ASGS structure, the SA3 of Armadale also has 708 new house building approvals. There were 456 approvals in the SA2 of Forrestdale - Harrisdale - Piara Waters, 128 in Armadale - Wungong - Brookdale, 38 in Kelmscott, 27 in Seville Grove, 26 in Camillo - Champion Lakes, 20 in Mount Nasura - Mount Richon - Bedfordale, 13 in Roleystone and zero in Ashendon - Lesley.

Forrestdale - Harrisdale - Piara Waters, which accounts for about 8% of Armadale SA3, had 64% of the total number of new house approvals.

In this case study, the ASGS has provided more detailed regional data than the ASGC.
CASE STUDY #2

In contrast to Case Study #1, this example from Queensland shows the converse. Here, the region has changed from five sparsely 'populated' SLAs (ASGC) to one SA2 (ASGS). As per Case study #1, there is a perfect outer boundary match - which we must remind users - is not always the case.




Under the ASGC there were three SLAs based on Barcaldine and two based around Blackall. With the new ASGS, however, a single SA2 combines the two main centres - renamed as Barcaldine - Blackall.




For the five SLAs under the ASGC (Map 2A), Blackall Tambo (R) - Tambo had zero approvals, while Barcaldine (R) - Aramac and Barcaldine (R) - Barcaldine had one approval each, and Barcaldine (R) - Jericho and Blackall Tambo (R) - Blackall recorded three approvals each (eight new house approvals in total). The new Barcaldine - Blackall SA2 (ASGS) also recorded eight approvals.

In this case study, the new ASGS provides a more consolidated SA2 region than the sparsely 'populated' SLAs.
CASE STUDY #3

This case study is an example of where a Statistical Subdivision (SSD) under the ASGC covers an apparently similar geographic area to two SA3s (ASGS).

Map 3A shows the SSD (ASGC) of Melton - Wyndham on the outskirts of Melbourne, with its five component SLAs.




Map 3B shows that under the ASGS, a slightly different area is covered by two SA3s (shown in bold boundary lines) and their component SA2s. For instance, the Bacchus Marsh SA2 is now included. Also, the former Wyndham (C) - North SLA (ASGC) has lost some land area to the new Werribee - South SA2 (ASGS). This is also an example of how the new ASGS region names are more closely related to localities than the (ASGC) SLA names (in Map 3A).




While this case study does not show a direct one on one transposition between boundaries like Armadale (Case Study #1), it does again highlight the more detailed information available from the ASGS. For example, under the ASGC, the SLA of Wyndham (C) - North recorded 632 new house approvals from July to December 2011. In contrast, under the new ASGS, this area is largely represented by Tarneit (with 313 approvals), Truganina (190), Laverton (73), Hoppers Crossing - North (7) and Hoppers Crossing - South (6) - or 589 new house approvals in aggregate.

This case study is an example of where an ASGC region is now represented by a quite different geography (in size, structure and region names). In this case, the ASGS can provide more detailed regional data at the SA2 level.
CASE STUDY #4

This South Australian case study is for the SLA of Mt Barker (DC) - Central in the ASGC, compared with the SA2 of Mt Barker (ASGS).




Map 4A shows the SLA of Mount Barker (DC) - Central, under the ASGC, while Map 4B shows the SA2 of Mount Barker under the ASGS.

There has been a noticeable change between the boundaries. For example, the locality of Nairne was previously contained within the Mount Barker (DC) - Central and Mount Barker (DC) - Balance SLAs, whereas now it is a distinct, separate SA2, to the north-east of the new Mount Barker SA2.




Despite such boundary changes, the Building Approvals data for both regions is very similar. Under the ASGC, Mt Barker (DC) - Central had 69 new house approvals for July 2011 to December 2011, whereas under ASGS, Mt Barker SA2 had 65 new house approvals.

This case study provides an example of how the data can appear similar, but relate to quite different geographic areas under the ASGC and ASGS.
CONCLUSION

These case studies have shown four different examples of the impact of the change from ASGC to ASGS, using Building Approvals data.

While the ASGS has delivered recognisable regions and in some cases more detailed small area data, two of the case studies also show the importance of understanding the differences in ASGC/ASGS boundaries and noting changes in region names.

To enable more effective interpretation of data under the ASGS, it is recommended that users:

• check the ASGC and ASGS maps to see where the boundary changes/differences are.
• check region names and do not assume that the ASGC/ASGS regions are the same because they have a 'similar' name.

FURTHER INFORMATION

ASGS maps can be downloaded from Australian Statistical Geography Standard (ASGS) - Volume 1: Main Structure and Greater Capital City Statistical Areas, July 2011 (cat. no. 1270.0.55.001).

If you are interested in other small area buildings data, or extensions to what has been covered in this article, you can visit our specialist data services page at the National Information and Referral Service (NIRS).