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I'm working right now a project looking at medical labour supply in rural areas in Australia. I aim to use STATA for most of this analysis, but a change in geographic standards by the Australian Bureau of Statistics has created a problem. To be more specific:

  • The program whose effect I am focussed on uses the old Australian ASGC 2006 Statistical Local Area (SLA) as a base
  • The ABS makes most contemporary data available using the newer ASGS Statistical Area level 2 (SA2) standard

Digital Boundaries are available for both of these on ABS Boundaries Online. I need to recast some of this contemporary data (Building Approvals, population, etc.) to the older standard. I am thinking of using a population grid (ABS Population Grid 2011) as a base on which to recast the data from one set of boundaries (SA2) to another (SLA2006). i.e. Look at the fraction of population in one SA2 that fits into the SLA, and transfer that much of the SA2's data to the SLA.

Any ideas on how I could do this in ArcGIS or QGIS?

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This is known as 'concording' (well, I thought it was, but I can't Google it, so it might not be).

Basically, it's a very difficult thing to do. It's unfortunate that the ABS change their boundaries every census, and the 'mesh blocks' were intended to stop this, I think, but even they change a bit.

Essentially, what you'd need to do is split up your FIRST dataset by the SECOND (your target standard), and apportion the statistics into those split parts somehow (probably by area). Next you can merge these split areas into the same areas as the SECOND dataset. Now you have two datasets with the same boundaries and the statistics have been altered to fit.

The issue is that people and houses are not distributed across an area evenly, so you're making assumptions and there's a risk you're not comparing like-for-like any more, so you need to communicate that.

  • I am rather new to GIS in general - in ArcGIS or QGIS how would I actually go about these calculations? As in, the actual commands to use? – laxmanb Sep 3 '15 at 5:39
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    It's a reasonably complex thing to do... Have a think about it. Come back if you haven't sorted it out and I'll see if I can help you out more. Look into the 'split' and 'intersects' functions and also into 'area' calculations, before you split, and afterwards. – Alex Leith Sep 3 '15 at 6:54

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