APPENDIX 2 DATA COMPARISON
COMPARISON OF DATA FROM ALLS AND OTHER ABS SOURCES
The ALLS collected data across a range of topics, some of which have been included in previous ABS surveys. Where possible question modules from existing surveys were used in the ALLS questionnaire to ensure the ALLS data is comparable with other surveys that users of the data may wish to compare with. However, given the ALLS is part of an international study of literacy, there was a requirement to use internationally developed question modules to ensure the results are comparable with other countries involved in the study.
There are other reasons why results from the ALLS may differ from other ABS surveys collecting information on the same topic. The ALLS is a sample survey and its results are subject to sampling error. As such, ALLS results may differ from other sample surveys, which are also subject to sampling error. Users should take account of the RSEs on ALLS estimates and those of other survey estimates where comparisons are made.
Differences may also exist in the scope and/or coverage of the ALLS compared to other surveys. Furthermore, the ALLS was collected over the period July 2006 to January 2007. Differences in ALLS data, when compared to the estimates of other surveys, may result from different reference periods reflecting seasonal variations, non-seasonal events that may have impacted on one period but not another, or because of underlying trends in the phenomena being measured.
Finally, differences can occur as a result of using different collection methodologies. This is often evident in comparisons of similar data items reported from different ABS collections where, after taking account of definition and scope differences and sampling error, residual differences remain. These differences often have to do with the mode of the collections, such as whether data is collected by an interviewer or self-enumerated by the respondent, whether the data is collected from the person themselves or from a proxy respondent, and the level of experience of interviewers undertaking the data collection. Differences may also result from the context in which questions are asked, i.e. where in the interview the questions are asked and the nature of questions that are asked beforehand. Because of the nature of such differences between statistical collections, the impacts on data are difficult to quantify. As a result, every effort is made to minimise such differences.
The following table, Comparison of Data from ALLS and Other ABS Sources, presents comparisons between a number of ALLS data items and similar data items from other ABS sources. As can be seen from the table, ALLS data is broadly consistent with other ABS sources.
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