Incrementality in digital marketing measures the additional value driven by a marketing action that would not have occurred without that action. Essentially, it aims to answer, ‘Did our campaign drive incremental results, or would they have happened organically?’

For example, if a company runs a paid social campaign and sees a spike in sales, incrementality helps determine how much of that increase was genuinely due to the campaign versus what might have happened without it.

Why Measure Incrementality?

Measuring incrementality is crucial for optimizing marketing spend and making data-driven decisions. Without it, marketers risk overspending on campaigns that might not actually contribute to their goals. Incrementality tests help marketers validate their investment by isolating the true impact of their campaigns, ensuring that they allocate budget to activities that genuinely move the needle.

Common Methods to Measure Incrementality in Digital Marketing

Here are some widely used methods to measure incrementality, ranging from broad approaches across channels to more granular tactics specific to paid social and paid search:

1.  Geo-Split Testing

Geo-split testing is one of the most common ways to test incrementality on a broad scale. This method divides geographic regions into test and control groups where only one group (test) is exposed to the marketing campaign, and the other (control) is not. By comparing performance in these regions, marketers can assess the lift attributable to the campaign.

2.  Holdout Testing

Holdout testing, sometimes referred to as ‘A/B testing,’ is another straightforward approach. It involves withholding the campaign from a small, randomized portion of the audience (control group) while targeting the rest (test group). By comparing results, marketers can determine the incremental lift caused by the campaign.

3.  Time-Based Testing

In time-based incrementality testing, campaigns run in alternating periods of activity and inactivity to see how KPIs fluctuate with and without the campaign.

Measuring Incrementality in Paid Social

Paid social is a popular channel for incrementality testing because of its broad reach and relatively high frequency, which makes it well-suited for testing various audiences and formats. Some specific techniques for paid social include:

1.  Conversion Lift Studies

Many social platforms, such as Facebook and Instagram, offer built-in tools for running conversion lift studies. These tools enable brands to measure the incremental conversions generated by a campaign by comparing a test group (exposed to the campaign) with a control group (not exposed).

2.  Audience Split Testing

Paid social platforms allow marketers to create specific audience segments for testing incrementality. This can be particularly useful for campaigns aiming to drive action in very targeted groups.

3.  Brand Lift Surveys

Brand lift surveys are an effective tool for understanding how campaigns affect brand perception, awareness, and consideration, even if they do not directly result in conversions. Facebook and

Instagram, for instance, offer brand lift studies to help measure these metrics.

Measuring Incrementality in Paid Search

Paid search typically targets high-intent users, making incrementality measurement somewhat unique due to the direct and intent-driven nature of search queries. Here are a few common methods:

1.  Keyword-Level Testing

One of the most effective ways to test incrementality in paid search is to evaluate specific keywords. By pausing or reducing bids on certain keywords, marketers can see if organic search fills the gap, thus revealing incremental impact.

2.  Geo-Split Testing in Search Campaigns

Geo-split testing can also be applied to paid search by running search campaigns in some regions and pausing them in others. This method allows you to see if conversions drop when search ads are not running.

3.  Auction-Based Experiments

Platforms like Google Ads offer auction-based experiments that let marketers test incrementality by varying bid strategies and evaluating conversion impacts.

Conclusion

Measuring incrementality is essential for understanding the true value of marketing efforts, helping marketers avoid over-attribution and optimize their budgets. With a variety of testing methods available, incrementality testing offers powerful insights across digital marketing channels. Whether optimizing paid social or paid search, incrementality testing provides clarity on what truly drives growth, helping brands allocate resources more effectively.