The NATSISS is conducted in all states and territories and includes remote and non-remote areas. The 2008 sample was 13,300 persons/6900 households, with a response rate of 82 per cent of households. In the 2008 NATSISS there was a relatively large level of undercoverage when compared to other ABS surveys. As a consequence, the analysis undertaken to ensure that results from the survey were consistent with other data sources was more extensive than usual. Potential bias due to undercoverage was addressed by the application of a number of adjustments to the initial weights and an adjustment to geographical areas based on the density of the Indigenous population. As undercoverage can result in variances across population characteristics, as well as across data items, caution should be exercised when interpreting the survey results. For more information see the 2008 NATSISS Quality Declaration. The SEW is conducted in all states and territories excluding very remote areas. This exclusion has a small impact only on national and state estimates, except for the Northern Territory, where such persons comprise over 20 per cent of the population. From 2009 the SEW will include remote areas but will exclude discrete Indigenous communities. As a consequence of this exclusion, comparisons between Indigenous and non-Indigenous people in remote areas are not available. The 2008 SEW response rate was 96 per cent. Both surveys are weighted to account for non-response. Since it is derived from sample surveys, this indicator is subject to sampling error which occurs because only a small proportion of the population is used to produce estimates that represent the whole population. Sampling error can be reliably estimated and is based on the statistical methods used to design surveys. Overall, this indicator has a relative standard errror (RSE) of less than 25 per cent for all states and territories. Finer levels of disaggregation (e.g. by the inclusion of other cross classifying variables) may result in higher levels of sampling error. |