Excess Share of Voice: The Growth Equation Marketers Forgot

Most marketers can tell you their ROAS. Almost none can tell you their excess share of voice.

That gap explains a lot of stalled growth.

ESov, the difference between your share of voice and your share of market, is one of the most reliably predictive metrics in marketing effectiveness research. Core findings from Les Binet and Peter Field's analysis of the IPA databank are straightforward: every 10 percentage points of excess share of voice is associated with roughly 0.5% annual market-share growth in B2C. LinkedIn's B2B Institute, working from a joint Binet/Field/LinkedIn analysis, puts the B2B figure even higher, at 0.7% growth per 10 points of ESOV.

Those numbers are modest enough that they're easy to dismiss. They're also compounding. Run 20 points of positive ESOV for three years and the math starts to get interesting.

Keeping this concept buried isn't about complexity. It's simple. What makes it uncomfortable is that ESOV forces a conversation most marketing teams actively avoid: are we spending enough to actually grow?

What ESOV Actually Measures

Nielsen defines share of voice as a brand's media spending as a percentage of all category media spending in a market, channel, and time period. Share of market is your revenue or unit share of the same category. ESOV is the gap between them.

If your brand holds 15% of category sales but accounts for 20% of category media spend, your ESOV is +5. Binet/Field research says that positive number should, over time, translate to market share growth. If your brand holds 15% of sales but only 10% of media spend, your ESOV is -5. You are, in effect, harvesting brand equity built in prior periods. That can work for a while. It doesn't work indefinitely.

This is why mental availability erodes quietly. You don't feel it when you cut. You feel it two or three years later when conversion rates drop and no one can explain why.

Behind this rule sits straightforward logic. Brands grow by reaching buyers who aren't currently buying them. As Byron Sharp and the Ehrenberg-Bass Institute have shown extensively, most category buyers are light or occasional purchasers who need to be reminded that your brand exists at the moment they're ready to buy. Outspending your market share means more of those buyers encounter your brand more often. Light buyers are the growth engine, and reaching them requires sustained presence.

Undercut that presence and the pipeline dries up, even if your bottom-funnel numbers look fine for another quarter or two.

The Metric You're Probably Using Instead

Here's the trap most digital-first brands fall into. They measure ROAS obsessively, optimize toward it constantly, and confuse efficiency with growth. The two are not the same thing.

ROAS is a rearview mirror. It tells you how well your ads captured demand that already existed. It tells you nothing about whether you're building the demand that will sustain you in 12 or 24 months. A brand running tight ROAS targets is almost certainly underinvesting in the upper funnel, which almost certainly means negative ESOV, which almost certainly means slower market share growth than their category position warrants.

Chapter 16 of Never Always, Never Never describes this dynamic directly. Patrick Gilbert covers the case of a global apparel brand running two completely separate teams, one focused on brand, one focused on performance, each optimizing for different goals in isolation. When AdVenture Media built a marketing mix model from years of campaign data, the results were unambiguous: brand campaigns were driving direct sales, and performance campaigns were building brand equity. The clean separation the client believed in didn't exist in the data. It existed only in the org chart.

ESov framework predicts exactly this finding. Brand spend and performance spend aren't pulling in opposite directions. Both contribute to the visibility that makes any downstream conversion possible. Binet and Field's 60/40 rule, derived from IPA data, reflects the same principle: roughly 60% of budget toward long-term brand building, 40% toward short-term activation. Skew too far toward activation, and you're essentially borrowing against equity you haven't replenished.

Answering the brand vs. performance split isn't an accounting question. It's a growth question.

Why Brands Underinvest in Voice Anyway

If the evidence is this clear, why do so many brands run persistent negative ESOV?

Organizational pressure, not analytical failure, drives this pattern. Brand spend is harder to attribute. It doesn't show up cleanly in a last-click report. When a CFO asks what the brand campaign drove, the honest answer involves a multi-year horizon and a probabilistic relationship between media weight and market share growth. That's a hard sell in a quarterly review against a performance campaign that shows a strong ROAS on the dashboard.

In Never Always, Never Never, Patrick Gilbert names this pattern the Wilt Chamberlain Effect. In 1962, Chamberlain shot free throws underhand and made 28 of 32. He knew it worked. He abandoned it anyway because it made him feel uncomfortable. The Wilt Chamberlain Effect isn't about ignorance. It's about choosing comfort over evidence. Marketers do this constantly with brand investment: the research is clear, the logic is sound, and still the budget gets cut because short-term pressure is louder than long-term proof.

The apparel brand in Chapter 16 made exactly this choice. Their VP of Paid Media acknowledged the data was compelling and the logic made sense, then asked whether it could be made to fit the existing structure instead. It couldn't. The team at AdVenture Media said as much directly. The model required the org to change, and the org wasn't willing to change.

That's not an unusual story. It's the norm.

ESOV in a Fragmented Media World

Original ESOV research was built primarily on TV-era data. Worth asking is how well it transfers to a media environment where U.S. retailers allocated 59% of ad budgets to digital, 29% to TV, and 7% to audio in 2025, according to Nielsen Ad Intel.

Honestly: the principle holds, but the measurement gets messier.

Digital channels have expanded what counts as "voice." Nielsen's spend-based definition is clean operationally, but practitioners now track SOV across search visibility, social mentions, earned media, and creator ecosystems. These aren't equivalent measures. A brand that dominates organic search rankings and earned social conversation but underinvests in paid media may have more effective voice than its spend-based ESOV suggests. Or it may not. Research on this is still developing.

What the data does support is that media mix matters within an ESOV strategy, not just total spend. An analysis of 600 Effie Award entries from 2018 to 2025 by Michele Arnese found that campaigns incorporating audio outperformed those without it on new-customer acquisition, brand distinctiveness, and pricing insensitivity. Audio represented 11% of total media spend on average among the high performers. That's a modest allocation producing a disproportionate return, which suggests brands running pure digital mixes may be leaving meaningful ESOV effectiveness on the table.

Relevant here too is the 95-5 rule. Most category buyers are not in-market at any given moment. They're not clicking on your search ads because they're not searching. Reaching them requires persistent, broad-reach media, the kind of media that builds brand salience over time. Audio, TV, and brand-oriented digital formats do this work. Pure performance media, almost by definition, does not.

The Growth Equation

ESov as a framework is not complicated. Spend above your market share, and you'll tend to grow. Spend below it, and you'll tend to shrink. IPA databank evidence behind this finding is the most rigorous long-run dataset in marketing effectiveness research, and it has held up across decades, categories, and markets.

What makes this equation so easy to forget is that the delay between cause and effect is long enough to break the connection in most organizations' measurement systems. Brand spend cut today shows up as market share decline months or years from now, by which point a dozen other explanations will seem more plausible to whoever inherited the P&L.

Answering the brand vs. performance budget allocation question ultimately comes down to a time horizon question. Are you managing this quarter or the next three years? Both matter. Research is clear that both work better together than either works alone.

Knowing that and acting on it are, as Wilt Chamberlain demonstrated, very different things.