Much of the recording of Census information from forms is now automatic, using scanning, Intelligent Character Recognition, and other automatic processes. Quality assurance procedures are used during Census processing to ensure processing errors are kept at an acceptable level. Sample checking is undertaken during coding operations, and corrections are made where necessary.
Once forms are received, they are checked for damage and errors, such as tears, multi-mark responses and illegible handwriting. These problems are fixed manually as the automatic coding process cannot handle errors of this type.
Most responses are coded automatically using official classifications with legal value checks built into the system. In addition a random sample of codes is checked manually against the original response on the form. Errors are more likely to arise during automatic coding of 'write in' answers. Clerical staff resolve problems that arise if text responses cannot be automatically matched to the index of possible responses. Their work is subject to a quality management process to ensure that errors are not being made.
The completed data are put through a series of automated checks to ensure internal consistency. The data are also scrutinised for changes over time, by comparison with previous Census data and other data sources, and across categories, where expected trends can be identified, and unexpected trends investigated.
In preparing Census data for output, various derivations and recodes are applied to the data to produce the variables listed in this dictionary. Data are processed further to create the range of Census data products. A series of checks occur at each stage of the output process to ensure data consistency and accuracy.