The Central Statistics Office has a statutory role in the co-ordination of official statistics in Ireland. In particular, it has the authority to ensure that appropriate standard classifications are used for this purpose. To this end, the Statistics Act 1993, 10(2), states that ’The Office (viz. Central Statistics Office) shall have authority to co-ordinate official statistics compiled by public authorities to ensure, in particular, adherence to statistical standards and the use of appropriate classifications.
A classification is an ordered set of related categories used to group data according to its similarities. It consists of codes and descriptors and allows survey responses to be put into meaningful categories in order to produce useful data. A classification is a useful tool for anyone developing statistical surveys. It is a framework which both simplifies the topic being studied and makes it easy to categorise all data or responses received.
It is generally accepted that a standard classification will usually meet a number of requirements which are outlined below.
Exhaustive categories - All survey responses need to fit into the classification structure somewhere
Precise and meaningful descriptors for categories - The content of each category in the classification should be clearly defined
Conceptually sound - The classification should have a conceptual basis and a logical structure
Statistically balanced - In general, survey responses should not fall heavily into one category and sparsely into the other categories
Operationally feasible - There is no point in having a classification that cannot be implemented in practice
Statistically robust - The classification should be able to be used for a number of years without revision
Internationally comparable - The classification should be comparable with any international standard classification