The base refers to everyone included in your analysis. Think of it as your reference point. By default, it represents all respondents in the data set you're analyzing. For example:

Here are three examples of when you might consider rebasing.

Let's say you're doing some analysis for a beauty brand who're launching a skincare product targeted at men, and have created an audience of "male internet users who’ve used 3 or more skincare products in the last week and want brands to be eco-friendly".

Here, you could apply a base of men to help you understand what makes your audience different from other male internet users.

Note: Because you're updating your point of reference, your indexes will refer to the "average male internet user aged 16-64" rather than "the average internet user aged 16-64".

We don’t like wasting people’s time, which is why we don’t ask our respondents irrelevant questions. For example, in GWI Core, we only ask respondents who own a vehicle about fuel type. This is known as routing.

When using the fuel type question, you may therefore want to apply a base of vehicle owners so you're only looking at those respondents who were asked the question.

Hint: Click the three little dots next to a data point in charts, select "view question" then click "notes" to find out more about the question and see whether any routing has been used.

We use multiple surveys to capture a broad range of data about internet users. Let's take a look at GWI Core as an example:

All of these components are weighted to represent the same overall universe of 16-64 year olds (and in some markets 16+), and can therefore be used together. This means you could be looking at something from the main survey, and then decide to pull in something from the brand and media module, and then something from GWI Core Plus.

This gives you loads of flexibility, but it also means you may have multiple bases active within the same chart or crosstab. This isn’t a problem. In fact, it’s how we recommend you keep things, as it means each data point and relationship is being calculated using the largest number of respondents possible. But if consistency is your priority, you can filter out anyone who didn’t answer all of the questions you’re using by applying a base of respondents who took part in the relevant recontact module or extension study.

Click the three dots on the base audience pill in the top-left corner, then select 'Replace'.

Click 'Add new base' in the upper-left corner.

When combining GWI Core with an add-on in charts, dashboards, or crosstabs, you can rebase to the audience size of that specific add-on. You can find the audience size of each add-on data set within the "survey details" folder.

Rebasing happens automatically. Your insights update based on your query, so there's no need to manually select a new base. Learn more about viewing rebased insights in Charts below.

When you select View full chart from a rebased Agent Spark insight, Charts displays the base information used to calculate the insight. This helps you understand which audience each result is compared against.

This view is available only when:

When multiple bases are used, attributes are grouped by their corresponding base audience. A dedicated Base column appears on the left side of the chart, making it clear which base applies to each attribute.

Selecting a base from the Multi-base dropdown automatically scrolls the chart to the relevant section.

You can also hover over a chart bar to view the base breakdown for that specific attribute.