Australian secondary school students' use of tobacco, alcohol, and over-the-counter and illicit substances in 2011
2.4 Data entry and cleaning
Questionnaires from all states and territories were catalogued by the Centre for Behavioural Research in Cancer at Cancer Council Victoria. Questionnaires were scanned and converted into data files, and were cleaned by a commercial market research firm. Cleaning followed the same procedures as used in previous survey years detailed in Appendix 2. Students with a large amount of missing data or whose responses were wildly exaggerated were removed from the data set before analyses started.