Search Incrementality Testing: Helping Advertisers Invest Where Growth Happens

Shopper behavior continues to evolve as consumers adopt new ways to discover, research, and purchase products. Search has long been a pivotal point into the purchase journey, connecting brands with consumers at moments of high intent – driven by need and/or upper funnel influence. More recently, emerging technologies such as AI-powered assistants and Large Language Models (LLMs) have introduced new discovery behaviors, creating additional pathways that influence how shoppers evaluate and purchase products.

While new paths have emerged in discovery, Search remains a key director of demand. The search inquiry exists, and it’s a question of if a brand is there to push it along the journey or allow another brand to fill that moment.

As customer journeys become increasingly fragmented across digital and physical touchpoints, advertisers face a growing challenge: determining how much of their sales performance is truly driven by Search and how much would have occurred regardless of investment. Without this understanding, brands risk overinvesting in channels that capture existing demand rather than generating new demand and not connecting their upper and lower funnel strategies.

The Challenge

Best Buy Ads is focused on maximizing advertiser sales by reaching consumers at the right moment across the entire shopping journey.

To optimize full-funnel media plans, advertisers need a clearer understanding of the incremental impact each channel contributes. Traditional performance metrics often attribute sales to Search without distinguishing between:

• Sales genuinely driven by Search advertising
• Sales that would have occurred organically without paid media investment
• The optimal level of Search investment relative to other media channels

Without an incrementality-based approach, budget allocation decisions can unintentionally prioritize attribution over actual business impact.

The Solution

Best Buy Ads launched its Search Incrementality Capability, a measurement framework designed to quantify the true incremental value generated by Search investments.

Using controlled experimentation, the capability isolates sales directly attributable to Search activity from sales that would have occurred naturally. The resulting insights enable media strategists and planners to make more informed budget allocation decisions and build full-funnel media plans grounded in incremental business outcomes rather than attributed performance alone.

The capability delivers:

• A clearer understanding of Search's true contribution to sales growth
• Incremental Return on Ad Spend (iROAS) measurements
• Data-driven budget allocation recommendations across channels
• Improved planning for omnichannel campaigns focused on maximizing total sales impact

Key Takeaway

As shopper journeys expand beyond traditional channels and new discovery experiences emerge, advertisers need measurement approaches that distinguish incremental growth from attributed performance.

Best Buy Ads' Search Incrementality Capability empowers advertisers to make smarter investment decisions by quantifying the true business impact of Search, helping allocate budgets more effectively across the full customer journey and ultimately drive greater incremental sales growth.

60x iROAS in Gaming, 18x in TV & Video, and 52x in Health & Wearables demonstrate that Search is not simply capturing demand, it is creating measurable incremental value when strategically deployed within a full-funnel media plan.

^{*Results are based on select case studies. Performance and iROAS outcomes will vary by brand, category, advertiser, and campaign execution.}