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Processing

Once all the paper forms have been collected, they are transported under secure arrangements to the Census Data Processing Centre (DPC). It is here that information on the forms is processed to produce the data that is then ready for use in a range of Census products.

The important process of workload reconciliation commences during enumeration and continues at the DPC after mail back, eform and census forms have been returned.

This process:

• reconciles actual dwelling counts to expected counts for every workload; and
• reconciles all relevant Census information from collectors (on their Collector Record Books) and from householders (on completed forms) to provide an accurate count of dwellings (and consequently persons) for each workload.

All paper forms received are checked to ensure that they are ready to be scanned and that any badly torn, stained or otherwise damaged forms are transcribed to ensure they will pass successfully through the scanning process.

Data will be captured and processed using similar technologies that were used successfully in 2006, including intelligent forms processing, and automatic coding (AC). Forms returned electronically will also be integrated into this processing methodology.

Manual intervention may be required to 'repair' unrecognisable characters from certain fields in the form. Once repaired, all fields for which written responses are provided are processed through the automatic coding system to create a computer data file containing only the classification codes. If a code cannot be automatically determined, then manual intervention via an online coding system takes place.

The use of images of Census forms dramatically reduces the need for the movement of large volumes of paper at the Census DPC.

First and Second Stage Processing

In order to release basic Census data as soon as possible, processing is split into two stages. In the first, simple topics such as age, sex and religion are processed. A high degree of automatic coding is achieved for these topics. Two of the key processes in First Release Coding include Workload Reconciliation and Family Coding. These processes are coverage checks to ensure that all dwellings and persons have been counted and progressed through DPC processes.

The second stage processes complex topics such as industry, qualifications and occupation, which require substantial manual intervention, via online coding, to allocate codes to the householder's responses.

Editing

Some editing is undertaken to reduce the inconsistencies in Census data. The types of errors that editing procedures can detect are limited to responses and/or codes which are invalid or inconsistent with other responses on the forms, or which are in conflict with Census definitions. An example of this is ensuring that the number of the month entered is not higher than twelve. Once detected, such inconsistencies are dealt with by changing one or more responses on the basis of decision tables drawn up for this purpose. Some inconsistencies will remain where it is impossible to determine the true situation from information provided on the Census form.

Imputed and Derived Data

During processing, certain procedures are applied for deriving or imputing some data items. Some data items are derived from other responses given on the Census forms. An example of a derived characteristic is labour force status. This characteristic is derived for all people aged 15 years and over and is determined using a decision table which takes into account the responses (or lack of them) given to several other questions on the form. These are: full or part-time job; job last week; looked for work; availability to start work and hours worked.

Data imputation is used for a small number of important demographic data items: age, sex, marital status and usual residence where responses have not been provided on the Census form. Imputation of missing data is a statistically sound process, that may also use other relevant information on the form.

Final Data

The final outcome of the Census DPC work is a file of coded records for each person, family, and dwelling enumerated in the Census. Once validated, the file becomes the source of all Census data. The data released in files and tables that do not allow the identification of individuals.

Archiving of Census Forms

Prior to 2001, forms and other name-identified records were destroyed once the statistical data required for the purposes of the Census was extracted.

As in 2006, the 2011 Census will give each person the opportunity to have his or her Census information kept by the National Archives of Australia and then made publicly available after 99 years. When all the statistical data has been extracted, the responses to the archiving question will be examined. Where a response to this question clearly indicates a respondent's agreement to have their Census information retained, and the form has been signed, the respondent's information will be transferred to the National Archives of Australia.

Recycling and Destruction

Once all the statistical data has been extracted, microfilming for retained records has been completed and the forms are no longer needed for processing, they will be pulped and turned into recycled paper and cardboard. The images of the Census forms used during processing and microfilming are also destroyed.