What is a Confidence Interval?

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A confidence interval is a measurement designed to help you figure out what your ideal customer does in the Great Southern region, the type of place they stay and the activities and experiences they seek out.

It's essential that this information is accurate and current, so you should identify how and when it was collected before relying on it.

For example, Tourism Research Australia (TRA) conducts two major surveys – the National Visitor Survey (NVS) and International Visitor Survey (IVS). Fact sheets are prepared on visitor numbers containing demographic and behavioural data for the Great Southern. The data contained in the Great Southern reports is extrapolated from the survey results. It is weighted and benchmarked, and estimates are developed across a three-year period. That means that the numbers that you see are a “best guess” based on a random sample of visitors surveyed in any given year.

To help businesses interpret the data they compile, Tourism Research Australia (TRA) publishes a confidence interval in each report. This gives important information about the sample size (how many people were surveyed) and how much confidence you should put in the results.

For example, the Overnight Visitor Survey 2019 for Australia’s South West estimates that 256,000 interstate visitors came to the region in 2019. The survey didn’t interview all these visitors – the results are based on a sample size of 299 individuals.

The 95% confidence interval for visitors is 13.2% - this means that the actual figure for interstate visitors is plus or minus 13.2% or 33,792 individuals. In other words, the actual figure may be anywhere between 222,208 and 289,792 (256,000 ± 13.2%).

Generally speaking, the lower the sample size, the higher the confidence interval (i.e. the more variation in the actual figure).