U.S. connected TV ad spending will hit $38B in 2026. That number has nearly doubled since 2022, and it will surpass traditional TV by 2028. But the uncomfortable truth behind all that growth is that 53% of marketing decision-makers say they would increase their CTV investment if they could actually prove it was working. Billions of dollars are flowing into a channel where most brands still can't draw a clean line between ad exposure and business results. The money is moving, but measurement hasn't caught up.

CTV's Rise Is Undeniable. So Is the Measurement Problem.

The audience shift is no longer a prediction. Streaming captured 47.5% of all television viewing in December 2025, shattering every previous record. On Christmas Day alone, streaming surged to 54% of daily TV usage and 55.1B viewing minutes. Cable sits at 24%. Broadcast at 20.5%. The living room screen now belongs to streaming.

Advertisers are following the eyeballs. IAB's 2026 Outlook Study projects 13.8% year-over-year growth in CTV ad spend, up from 11.4% in 2025. Only social media is growing faster. And the pipeline keeps expanding, too. Retail media networks alone are expected to sell $4.99B in CTV ads this year, rising to $10.28B by 2028.

But scale has created a fragmentation problem that traditional TV never had. Seven different companies now rank among the most-watched streaming platforms. Only three are expected to capture more than 10% of CTV ad sales in 2026. Each platform operates within its own data silo, its own reporting framework, its own definition of success. It may feel as if there is no universal standard for tracking ad exposure across these environments.

This is why 72% of ad buyers now cite cross-platform measurement as a top priority for 2026, up from 64% in 2025. And it's why 52% of senior marketers identify the lack of unified measurement as the single biggest barrier to omnichannel success.

Dan Larkman, CEO of Keynes Digital, put it plainly to eMarketer: "If you want CTV to behave like a performance channel, you have to measure it with the same discipline you'd apply to anything that affects revenue."

What Marketers Are Actually Measuring (And Why It's Not Enough)

Most CTV advertising measurement today stops at surface-level indicators. Industry data shows 86% of advertisers prioritize reach and frequency, while 85% emphasize brand lift as their key reporting metrics. CTV consistently delivers video completion rates of 90%+. These numbers look good in a dashboard but they tell you almost nothing about whether those impressions created a single new customer.

The deeper problem is attribution. With so many brands still relying on last-touch models, CTV rarely gets credit for the business outcomes it drives. Brands see paid search and social converting, assume those channels deserve the budget, and starve the CTV campaigns that actually warmed up those buyers in the first place.

This measurement gap has real consequences at the executive level. NielsenIQ's "CMO Outlook: Guide to 2026" report found that only 69% of marketing leaders believe their CEOs and CFOs support long-term brand investment. That's an 11-point drop from 2024. Meanwhile, 84% of CMOs now view short-term ROI as their primary metric for budget allocation. The pressure to prove immediate returns is winning, and brand investment is losing.

Gartner's research reveals the extent of the damage this cycle causes. A 2025 survey of 426 senior marketing leaders found that 84% of companies are trapped in what Gartner calls a brand "doom loop", where underfunded measurement leads to unclear impact, which breeds C-suite skepticism, drives tighter budgets, and further degrades measurement capability. Companies caught in this loop are half as likely to exceed their growth targets. Gartner predicts that by 2027, over 40% of CMOs who push for larger brand budgets will lose influence with the C-suite because they simply cannot demonstrate the returns.

WARC's 2025 Multiplier Effect report quantifies the stakes. Their analysis, developed with Analytic Partners, BERA.ai, Prophet, and System1, found that switching from a performance-only strategy to an integrated brand-plus-performance approach boosts total revenue returns by 25% to 100%. The median uplift is 90%. The relationship between brand and performance isn't additive–it's multiplicative. Unfortunately, you can't capture that multiplier if you can't measure it.

Incrementality Testing Changes Everything for CTV

CTV incrementality testing answers the question that attribution models cannot: did this campaign cause new business outcomes, or would those outcomes have happened anyway?

One reliable method is geo-based holdout testing. It works by dividing comparable geographic regions into test and control groups. CTV campaigns run in the test markets. Control markets see no CTV ads. After four to eight weeks, you compare business metrics across the two groups and calculate the incremental lift CTV actually delivered.

The math is straightforward. Incremental conversions equal test conversions minus control conversions. Incremental ROAS equals the value of those incremental conversions divided by media spend. These formulas strip away the noise of organic demand and give you the true causal impact of your CTV investment.

BCG validated this approach in a 2025 global survey of 3,000 senior measurement professionals. They found that 46% of marketers now use the measurement "trifecta" of marketing mix modeling (MMM), incrementality testing, and multi-touch attribution. But only the leading organizations, roughly 19% of the sample, truly integrate all three. Among those leaders, 40% use incrementality test results to calibrate and validate their MMMs. One case study from BCG's research illustrates the payoff: a major streaming company spending $500M across more than 10 channels, building granular MMMs calibrated monthly through geo-based experiments. The result was a 20% improvement in marketing spend efficiency and stronger buy-in from finance stakeholders.

Les Binet, co-author of The Long and the Short of It and one of the most cited voices in advertising effectiveness, frames the underlying dynamic: "When you have a strong brand, people will be more responsive to your performance marketing. They're already warmed up." His research with Peter Field, spanning nearly 1,000 case studies, shows that 60% of advertising payback comes from long-term brand building. Incrementality testing is how you prove that payback exists.

The Cross-Channel Multiplier: CTV + Search + Social

Connected TV brand advertising ROI becomes clearest when you measure CTV's influence on other channels. The Trade Desk ran this analysis across its own campaigns and found that when a user saw a CTV ad, the likelihood of searching for the brand and clicking a paid search ad increased by 232%. CTV tripled the effectiveness of paid search.

At the platform level, the Amazon and Roku partnership announced in 2025 now gives advertisers access to 80 million U.S. CTV households, covering over 80% of the market. Early tests showed that advertisers reached 40% more unique viewers without changing their budgets, while reducing ad redundancy by 30%. Deterministic, closed-loop CTV attribution connecting ad exposure to Amazon purchases is now available across this combined footprint.

This is why the BCG and Google Global Measurement Survey found that 80% of organizations already using the full measurement trifecta plan to increase their usage further. They've seen what a unified CTV measurement framework reveals, and they want more of it.

What a Precision CTV Measurement Framework Looks Like

A CTV measurement framework built for precision starts by replacing vanity metrics with causal ones. Completion rates tell you an ad played while incremental lift tells you it worked. Here are the metrics that should anchor every CTV brand campaign:

• Incremental lift measures the causal increase in conversions between exposed and control audiences.

• Incremental ROAS (iROAS) calculates revenue per dollar of CTV spend, net of organic activity.

• Cross-channel halo quantifies the lift that CTV exposure provides across search, social, and direct-response channels.

• Brand awareness lift, which Comscore research shows averages 25% for CTV campaigns, captures the upper-funnel impact that takes weeks or months to convert.

• Incremental CPA reveals your true customer acquisition cost by subtracting conversions that would have occurred without advertising.

A Nielsen study commissioned by Google reinforces why this discipline pays off. The research found that a 1% increase in brand awareness drives a 0.4% increase in short-term sales and a 0.6% increase in long-term sales. Brand advertising has a measurable near-term impact when you have the right CTV advertising measurement system in place.

Peter Field's analysis of the IPA Effectiveness Databank adds historical weight. TV appears in 80% to 85% of effective advertising cases over the past decade. The campaigns that win IPA Effectiveness Awards don't just run brand ads. They measure them using sophisticated frameworks that capture pricing power, acquisition efficiency, and long-term equity. Then they use those results to build an airtight investment case for the C-suite.

The brands that win in 2026 will operationalize CTV incrementality, every week, on every buy. That’s exactly what Agility does. Our platform runs CTV incrementality experiments, quantifies incremental conversions and revenue across your full funnel, and feeds that intelligence back into your audience, budget, and creative decisions. Instead of walking into budget meetings with completion rates and anecdotes, you walk in with iROAS, incremental CPA, and cross-channel halo proof that your CTV investment is creating new buyers at a price your CFO will greenlight. If you’re serious about turning CTV into a precision growth engine, it’s time to put Agility at the center of your brand advertising stack. Get started with Agility today.

FAQs

What is CTV incrementality measurement?

CTV incrementality measurement shows how many conversions or how much revenue your CTV campaigns caused that would not have happened without the ads, usually by comparing exposed vs. holdout groups.

Why isn’t reach and completion rate enough for CTV?

Reach and completion rate tell you how many people saw your ads and finished them, but they don’t show whether those impressions generated any net-new customers or revenue. Incrementality fills that gap by measuring true lift.

How does CTV incrementality work with MMM and other measurement tools?

Incrementality results can be fed into your marketing mix models and attribution tools to calibrate them, ensuring that the long-term brand impact and short-term performance impact of CTV are accurately reflected in your broader measurement framework.