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​​Key methodological changes to the International Visitor Survey (IVS) and National Visitor Survey (NVS) are detailed below.

Due to the changes to the NVS methodology, domestic visitation estimates for the March quarter of 2014 and onwards are not directly comparable with estimates from the December quarter 2013 and prior. Additionally, original domestic estimates for 2014 to 2016 were revised and reissued in 2017. Therefore, domestic estimates for 2014 to 2016 published in year ending December 2016 and prior publications should not be used.

Due to the back-casting of the IVS estimates, data in Tourism WA publications for the period year ending (YE) December 2013 and future releases should not be compared with previously published reports/factsheets (i.e. YE September 2013 or prior reports).  Please note these changes affect all Tourism WA publications based on IVS data.

National Visitor Survey (NVS) - Methodology

Tourism Research Australia’s (TRA) National Visitor Survey (NVS) commenced in 1998. Between 1998 and 2013, all interviews were undertaken with respondents on residential fixed-line telephones using Computer Assisted Telephone Interviewing (CATI).

The mobile phone only population in Australia has increased substantially in recent years. Given this, to provide better coverage of the Australian population, TRA commenced mobile phone interviewing on 2 January 2014. From 2014 onwards, 50% of the NVS sample is interviewed on fixed-lines, and 50% on mobile phones, also known as a ‘dual-frame sample’ methodology.

Analysis by TRA has revealed people interviewed on mobile phones are different to people interviewed on landlines in terms of their demographic profile and travel behaviour. Most notably, people interviewed on mobile phones are more likely to be from a younger demographic group who are inclined to travel more frequently. The inclusion of mobile phone interviewing has improved visitation estimates by bringing the sample more in line with the Australian population. However, the change in methodology means there is a ‘break in time series’ and domestic estimates for 2014 onwards are not directly comparable to domestic estimates for previous years. It is important to keep this change in methodology in mind when looking at long term trends in the NVS results.

In September 2016, TRA confirmed there was a methodology issue with the NVS impacting the domestic estimates for all States and Territories. TRA have now corrected the issue and all domestic estimates from the commencement of the dual frame data collection (2014 to 2016) have been back cast and reissued. Revisions have been made for all States and Territories and across all purposes of travel, although WA was one of the most impacted States. 2014 and 2015 estimates have seen the most significant revisions; only minor revisions were required for the 2016 estimates as they were less impacted by the methodology issue. Domestic estimates for 2014 to 2016 published in previous Tourism WA or TRA publications (year ending December 2016 or earlier publications) should no longer be used.

By correcting this methodology issue the revised estimates for 2014 to 2016, and estimates produced by the NVS moving forward, more accurately reflect the Australian population and domestic travel across the country.

​​International Visitor Survey (IVS) - Weighting Methodology

Tourism Research Australia's (TRA) International Visitor Survey (IVS) is benchmarked to and weighted against Short Term Visitor Arrivals from the Overseas Arrivals and Departures (OAD) data published by the Australian Bureau of Statistics (ABS). The ABS has recently improved its approach to imputing missing values in the OAD data, and as a result, has back-cast the OAD data to July 2004 to ensure a comparable time series. Therefore, TRA have back-cast the IVS data to July 2004, resulting in revisions to all published IVS data. This change in methodology means that estimates are improved, and the subsequent back-casting allows users to continue to use the full time series for trend analysis and comparative purposes.

Due to the methodology change detailed above and the subsequent revisions to the IVS data, Tourism WA publications for the period year ending (YE) December 2013 and future releases should not be compared with previously published reports/factsheets (i.e. YE September 2013 figures or prior).​

Last Reviewed: 2017-10-17