About Census Classifications
What is a classification?
The Census gathers information on a number of topics about persons, families and dwellings.
Each topic is represented on the Census form by one or more questions. For example, a topic about dwellings, 'Dwelling internet connection' is represented by a single question whereas there are six questions related to the 'Labour force status' of people aged 15 years and over. The questions collect information about a particular data item, called a variable. A variable may take a range of values. The Dwelling internet connection question is based on a simple yes/no question and so the variable has two values. The Labour force status variable has six values ranging from Employed, Worked full-time to Not in the labour force.
The range of values available for a variable is referred to as its classification. Each value of a variable is referred to as a category, or class, of the classification. Most classifications in this dictionary also include supplementary codes which are not a formal part of the classification but are needed to account for situations where the question was not applicable, was not answered, or was not answered in sufficient detail. This applies to Dwelling Internet connection which has two supplementary codes in addition to the two categories for the 'yes' and 'no' answers to the question.
For efficient computer processing, and for specifying the order in which the categories of a classification are presented in a table or report, the categories of a classification are recorded in computer records as numbers. For the variable Dwelling internet connection, the category 'internet accessed from dwelling' is represented by the code number '1', the category 'internet not accessed from this dwelling' is represented by the code number '2' and the supplementary categories are represented by symbols (Not stated by '&' and Not applicable by '@)'). Typically a classification is defined by a list of category descriptions and their corresponding codes.
Computer processing of Census forms following a Census is largely concerned with the allocation of appropriate codes from the responses to the questions on the form. However, when tables are generated from the coded Census file, the classifications making up the table are usually presented in terms of their category descriptions as well as, or in place of, their code.
The Census uses Australian standard classifications where available and appropriate. Examples of these are the Australian and New Zealand Standard Classification of Occupations (ANZSCO) and the Standard Australian Classification of Countries (SACC). These Australian standard classifications are used as the basis for Census output classifications, such as Country of Birth of Person, which uses SACC. Australian standard classifications are reviewed on an irregular basis to reflect changes in Australian society. A summary of any changes to these classifications is provided in the previous section 'What's New for 2016' - New and Revised Classifications'.
Where an Australian standard classification is not available, classifications specific to Census variables have been developed. Examples of such Census classifications are Child Type, Dwelling Internet Connection and Method of Travel to Work. The categories of these classifications are reviewed prior to each Census. A summary of changes to Census variables is provided in the previous section 'What's New for 2016 - Summary of Changes to Variables 2011 to 2016'.
Dwelling Internet Connection can be used as an example of the presentation of classifications in this dictionary. The parts of each classification are:
Top row: a mnemonic (NEDD), the name of the classification, and the release phase.
Second row: an icon reinforcing the message about the unit the classification relates to, and a description of the classification.
Third row: specifies the applicable group for the variable - in this case, occupied private dwellings. For the classification labour force status, the applicable population would be people aged 15 years and over.
Fourth row: lists the categories and their numeric or character codes.
Fifth row: states the number of categories at each hierarchical level of the classification
Sixth row: details the make-up of the not applicable category. In this case, the Internet dwelling connection question is only asked of households in private dwellings, and so the not applicable category is made up of unoccupied private dwellings, non-private dwellings and also people covered by the special purpose codes 'Migratory, off-shore and shipping SA1s'. These are created for people who are located on long distance transport; offshore rigs and drilling platforms; or on vessels in Australian waters, in or between Australian ports.
- Mnemonics are a shorthand method of describing Census classifications when specifying output requirements. Each classification relates to either a dwelling (or household), family or person. The last character of the mnemonic (D, F or P) indicates the unit to which the classification relates.
- Census data items are released in phases. For 2016, the release phases are June and October 2017. The June 2017 release will include most data items and geographies, while data items that are complex and time-consuming to process are released in October 2017.
|NEDD ||Dwelling Internet Connection|
| ||Records whether any member of the household accesses the internet from the dwelling. This includes accessing the internet through a desktop/laptop computer, mobile or smart phone, tablet, music or video player, gaming console, smart TV or any other devices . It also includes accessing through any type of connection for example ADSL, fibre, cable, wireless, satellite and mobile broadband (3G/4G).|
|Applicable to:||Occupied private dwellings |
|Categories:||1||Internet accessed from dwelling|
|2||Internet not accessed from dwelling|
|&||Not stated |
|Number of categories: ||4|
|Not applicable (@) category comprises:|
Unoccupied private dwellings
Migratory, off-shore and shipping SA1s|
Related glossary entries
Classifications are designed to be a simple technical guide to the key aspects of the classification. There is often also a glossary entry about the data item. The glossary items may include information such as changes in the classification over time and particularly since the last Census; aspects of interpreting the data for the item; and have links to other related glossary items. In addition, the glossary provides information about some of the terms used in the classification. For example, the glossary includes entries Dwelling Internet Connect (NEDD) which gives some history on this data item, Dwelling type (DWTD) which defines occupied private dwelling and other dwelling types and Residual categories and supplementary codes, which explain the categories Not stated and Not applicable.
Recodes and user defined fields
It is important to realise that the classification categories can be recoded and categories from different classifications can be combined using user defined fields. For example, if there was interest only in households where no-one accessed the internet, the classification could be recoded to consist only of category 1, Internet not accessed from dwelling and this could be used to become the population of a table. The characteristic of households who do not access the internet could then be the focus of the tables produced.
A user defined field can bring together categories of different classifications, including classifications of different levels (dwelling (households), family, person), to make a new data item.
For more information see Recodes and user defined fields in the glossary.
For details on the geographic classification which underlies all Census data see Australian Statistical Geography Standard (ASGS) in the glossary.