Introduction

Australian spatial data, in my opinion, is very confusing. According to The Australian Statistical Geography Standard (ASGS), our spatial structure is split into 2 groups: the ABS Structures and the non-ABS Structures.

ABS Structures

Non-ABS Structures

As you can see above, ABS and Non-ABS structures do not always overlap. From my own observation, I think that most of the Australia-related datasets normally use postcode/suburbs as the spatial structure. But keep in that in Australia, postcode and suburb do not always align. Some postcodes can have multiple suburbs. Furthermore, there are postcodes that can span across the state borders, for example:

Postal Area     Postal Areas that cross state or territory borders
POA 0872        Postal Area 0872 crosses into NT, SA and WA
POA 2540        Postal Area 2540 crosses NSW and OT (Jervis Bay)
POA 2618        Postal Area 2618 crosses NSW and ACT
POA 2620        Postal Area 2620 crosses NSW and ACT
POA 3585        Postal Area 3585 crosses Vic. and NSW
POA 3644        Postal Area 3644 crosses Vic. and NSW
POA 4383        Postal Area 4383 crosses Qld and NSW
POA 4825        Postal Area 4825 crosses Qld and NT

Recommendation

Working with postcode and suburbs can be tricky. Postcode boundaries are approximations. What we can do is to use the POS_Shapefile from the ABS to make it more accurate. Furthermore, suburb boundaries aren’t available from Tableau. If you use Postcode boundaries with suburbs’ names, you will notice some of the suburbs are missing. The reason being that one postcode can have multiple suburbs. Similarly, you can use SSC_Shapefile from the ABS in Tableau to have better representations.

In conclusion, if the dataset used postcode as their locality, we can just go ahead and use the postcode as the geometry input to Tableau. But, if they used suburbs as the representation, we shouldn’t or even wouldn’t use postcodes as the geometry input in Tableau. Your analysis will be telling lies and present inaccurate information to viewers. Even worse, it can cause financial loss to your business or clients. Try to be vigilant and cautious when dealing with Australian spatial data in Tableau.