Sunday, 23 July 2017

2016 Census Carwoola: Age and Ancestry for Gazette area

The only place to begin this is with a discussion of what is meant by Gazette area.  In using Table Builder for the 2011 Census Results I combined 3 State Suburbs (Carwoola (CA), Hoskinstown (HO) and Primrose Valley (PV)) to approximate the catchment area as shown in the graphic below.  I noted that the area for Primrose Valley was not right, as the boundary crossed the Queanbeyan River to include Urila.
 In starting "work" on this post I was surprised to find that the populations of Hoskinstown and Primrose Valley had dropped by about 50% between 2011 and 2016.  This led me to look at the ABS Geography pages which showed that those two suburbs had both been split (which was not at all apparent as the same name had been retained).

Carwoola appears to be the same in 2016 as in 2011.  Primrose Valley has been split with parts now going to Urila (U) and Yarrow (Y) neither of which existed (nor indeed exist) in the State Suburb list for 2011. Hoskinstown has had 3 parts split off going to Forbes Creek (FC); Rossi (R) and Palerang (P).  It is possibly not the fault of ABS as their "Maps" page includes these boundaries (along with Electoral and Postal boundaries) as Non-ABS structures.    However, IMHO they should have a good hard look at how the boundaries are presented in Census output.

Another note for caution: "our" area is Palerang and the State Suburb of Palarang is much further South - close to Dalgety.

Here is the map of suburbs in the Gazette Catchment (or at least included therein in 2011).
The 'recognition' of Yarrow has little effect on analysis as there are no more than 15 people (and perhaps as few as 8) in that area .  With so few people the Census data are intentionally unstable to preserve confidentiality.  Palerang has zero population.  All the other 'new' suburbs have non-trivial populations.  

Population size and Age

Having combined the new suburbs to match the old definitions gives this comparison:
Carwoola and Hoskinstown show a slight - but puzzling - decrease since 2011 while Primrose Valley show some growth.
Using a polynomial to remove the random noise from age profiles shows very similar patterns in 2011 and 2016 for the Gazette area in total.
Getting back into detail here are the State Suburb populations for the Gazette area (plus Urila).


I decided that my second foray into the first tranch of data would be to look at ancestry: if there was a marked change in response rates between 2011 and 2016 I would have expected that to show up here as a major increase in "Not Stated".  In fact the % of records with no ancestry stated has declined slightly since 2011.  Possibly this is an effect of many forms being completed on line.

Looking at the incidence of Not Stated Ancestry and Imputation of age, in most suburbs it appears that in most cases a response of "Not stated" for ancestry means that the age was imputed (ie no form was received for a household).  In a couple of smaller suburbs an unusual situation appears in which the number of records for which age was imputed is greater than the number with Ancestry not stated.  I can only conclude that this is either:
  • an artefact of the confidentiality provisions; and/or
  • because a few people completed a hard copy form and the answer for age was not legible; and/or
  • because a few people are amazingly sensitive about their age!
At the most detailed (4 digit)  level of the ancestry classification, 35 ancestries were reported in 2011 and 30 in 2016.  Overall:
  • the number of people reporting each ancestry correlates very well (coefficient of 99.4%) between the years;  
  • The 5 most common "ancestries" English (EN), Australia (AU), Not Stated (N/S), Irish (IRE) and Scottish (SCO) appear in the same order in both years. Italian (now 6th) and German (now 7th) swapped places;  
  • 8 ancestries maintained the same rank, 14 moved up the list and 16 dropped down; 
  • 8 ancestries  disappeared between the Censuses while 3 others were added in 2016.
In view of these fairly marginal changes the ancestry profiles are very similar when shown as pie charts.

Looking at the individual suburbs tends to give a similar picture to the above although, with the much smaller population sizes for suburbs other than Carwoola, the domination of Australian and English is more evident.  It is also possible that a relatively high percentage (eg one ancestry in Rossi is 4% against the value of 1% for the total area) could be attributed to a single family.

My broad conclusion from this exercise is that the information for 2016 is consistent with that from 2011.  My reservation about the quality of the data continues to be a concern that some dwellings were not identified by the Collectors

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