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TECHNICAL NOTE 2 DATA QUALITY
5 Error other than that due to sampling may occur in any type of collection, whether a full census or a sample, and is referred to as non-sampling error. All data presented in this publication are subject to non-sampling error. Non-sampling error can arise from inadequacies in available sources from which the population frame was compiled, imperfections in reporting by providers, errors made in collection such as in recording and coding data and errors made in processing data. Errors also occur when information cannot be obtained from all businesses selected. The imprecision due to non-sampling error cannot be quantified and should not be confused with sampling variability, which is measured by the standard error.
6 Although it is not possible to quantify non-sampling error, every effort is made to reduce it to a minimum. Collection forms are designed to be easy to complete and assist businesses to report accurately. Efficient and effective operating procedures and systems are used to compile the statistics. The ABS compares data from different ABS and non-ABS sources, to ensure consistency and coherence.
7 Differences in accounting policy and practices across businesses and industries can also lead to some inconsistencies in the data used to compile the estimates. Although much of the accounting process is subject to standards, there remains a great deal of flexibility available to individual businesses in the accounting policies and practices that they adopt.
8 The above limitations are not meant to imply that analysis based on these data should be avoided, only that the limitations should be borne in mind when interpreting the data presented in this publication. This publication presents a wide range of data that can be used to analyse business and industry performance. It is important that any analysis be based upon the range of data presented rather than focusing on one variable.
9 In the 2010-11 Economic Activity Survey (EAS), there was an 87.5% response rate from all businesses in the Transport, Postal and Warehousing industry division that were surveyed and found to be operating during the reference period. Data were imputed for the remaining 12.5% of operating businesses. This imputation contributed 6.9% to the estimate of Income from transport services for the Transport, Postal and Warehousing industry division.
Comparison with other ABS statistics
10 In some cases estimates given in this publication may differ slightly from those from other sources. These differences may be the result of sampling or non-sampling error, or may result from differences in scope, coverage, definitions or methodology.
11 Care should be taken when comparing the 2010-11 estimates with transport related estimates released as part of Australian Industry, 2009-10 (cat. no 8155.0) because of changes in question wording, sample design and conceptual definitions. Refer to In this issue for more detail on data comparability between the two years.
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