Most of what marketers believe about brand choice, that growth comes from loyal fans who love the brand, is contradicted by some of the most reliable patterns in all of marketing science. The unglamorous truth is that brands grow by being bought by more people, more of whom barely think about them, and the game is mostly about being easy to remember and easy to buy.
The starting point is deflating and liberating at once: brand choice, in most repeat-purchase categories, behaves less like a story of relationships and love and more like a stochastic, near-stationary process, a stable statistical pattern of buying that barely changes year to year. Ehrenberg spent decades documenting regularities so consistent across categories, countries, and decades that the field calls them empirical generalisations, and they are among the most reliable findings marketing has (Ehrenberg, 1972).
The workhorse is the NBD-Dirichlet model, a statistical description of how often people buy a category and which brands they pick, which predicts a brand's buying patterns remarkably well from almost nothing but its market share (Ehrenberg, Uncles and Goodhardt, 2004). Out of it fall the laws that overturn marketing folklore.
The first is double jeopardy. Smaller brands are punished twice over: they have fewer buyers, and those fewer buyers are also slightly less loyal, buying the brand a little less often than big brands' buyers buy theirs (Ehrenberg, Goodhardt and Barwise, 1990). Loyalty, in other words, is mostly a function of size, not of how much people love the brand. The cherished small "cult" brand with a devoted following is largely a myth; on the data, small brands have less loyal customers, not more.
The second is duplication of purchase. A brand's buyers are not a walled-off tribe; they also buy competing brands, and they do so roughly in proportion to those competitors' market shares. Your customers are mostly other brands' customers too, shared out according to how big each rival is, which means brands in a category compete for the same pool of largely promiscuous buyers rather than each owning a loyal segment.
Sharp turned these findings into a practical doctrine in How Brands Grow: because loyalty is capped and size-driven, growth comes overwhelmingly from penetration, getting more people to buy you at all, not from squeezing more loyalty out of existing customers. That reorients strategy toward reach over narrow targeting, toward the light and occasional buyers who make up most of any brand's volume, and toward being easy to buy (physical availability) and easy to remember (Sharp, 2010).
The "easy to remember" half is developed in How Brands Grow Part 2 as mental availability: the probability that a brand comes to mind in a buying situation. It is built and measured through category entry points (CEPs), the specific cues, occasions, needs, and contexts that send someone looking to buy, "something quick for the kids' lunch", "a treat after a hard week", "a gift that looks thoughtful". A brand is mentally available to the degree it is linked in memory to many of the CEPs that actually occur, and this salience, being readily thought of across buying situations, is what the framework optimises (Romaniuk and Sharp, 2016; the salience concept is Romaniuk and Sharp, 2004).
Standing against this behavioural tradition is the brand-equity school. Aaker and Keller built brand equity around meaning: a brand as a network of associations, beliefs, and feelings in the consumer's mind, whose differentiation and perceived value are the real assets (Aaker, 1991; Keller, 1993). Where Ehrenberg-Bass sees a stochastic buying machine best served by availability, the equity tradition sees meaning and difference as what earns a brand its place and its price.
The honest picture is a genuine, unresolved tension, not a knockout, and getting it right matters because both camps overclaim.
The empirical generalisations are remarkably solid. Double jeopardy, duplication of purchase, and the Dirichlet patterns replicate across categories, countries, and decades to a degree most of social science can only envy, and, worth stressing for anyone working internationally, this is one of the few marketing findings that genuinely travels rather than being a quirk of one wealthy Western market. But their power comes with a boundary: they describe stationary markets quite well while they describe disrupted ones poorly. New entrants, categories being redefined, subscription and platform lock-in, and fast-growth or emerging markets are exactly where the near-stationary assumption strains and the laws bend, so the doctrine is strongest for established brands in mature, stable categories and weakest at the disruptive edges where a lot of the interesting growth happens.
The penetration-over-loyalty doctrine is true on average and genuinely corrective, but "on average" hides real exceptions. In luxury, in high-involvement and B2B categories, in subscription businesses where retention economics dominate, loyalty and premium do real work that the volume-from-penetration story underplays. Treating "growth is always penetration" as an absolute is as much a mistake as the loyalty myth it corrects.
The sharpest live dispute is distinctiveness versus differentiation. Ehrenberg-Bass argues that perceived differentiation (being meaningfully different) is weak and overrated, and that what matters is distinctiveness (being recognisable, ownable assets that make a brand easy to identify and recall). The equity camp counters that meaningful differentiation is precisely what drives penetration over the long run and is exactly what the behavioural laws, being descriptions of stationary states, cannot see. The defensible synthesis: distinctiveness is very well evidenced and undervalued by traditional brand thinking, while differentiation is contested but not dead, especially over long horizons and in the disrupted markets where the Dirichlet laws are weakest.
Finally, a practical caution about CEPs: the framework is genuinely useful but easy to abuse. A "CEP audit" that lists forty entry points becomes a taxonomy-filling exercise rather than a discipline, and the discipline is what matters, which moments actually drive purchase and how often they occur. A CEP list without frequency and importance weighting is a decoration, not a strategy.
The evidence base is strongest for frequently-bought, packaged-goods-style categories and thinner for durables, services, and truly novel products. It describes stable states well and transitions poorly. And because the laws are so robust, there is a temptation to treat them as universal and skip the check of whether a given market is actually stationary, mature, and structured like the ones where the laws were derived.
How far do the empirical generalisations hold in fast-growth and emerging markets, and in digital and subscription categories with different retention dynamics? Can the distinctiveness-versus-differentiation dispute be settled with long-run rather than snapshot data? And is mental availability genuinely separable from the "meaning" the equity school insists on, or are they two descriptions of the same underlying thing?
The usable core: brands grow mainly by reaching more buyers and being easy to recall and buy, loyalty is largely a size effect rather than proof of love, and the reliable levers are penetration, distinctiveness, and mental availability, held as strong priors to check against a market's actual structure.
This is the most useful and most disorienting body of evidence in marketing, and internalising it changes where money goes. Anchor brand diagnostics on penetration and mental availability before loyalty and love, because the loyalty and "brand love" metrics that dashboards celebrate are largely artefacts of size (double jeopardy), and mistaking them for the cause of success leads to over-investing in loyalty schemes for existing customers when growth almost always comes from reaching new and light buyers (Sharp, 2010). Put the diagnostic order plainly: measure how many people buy you and how readily you come to mind at the moment of need first, and only then ask about affection or advocacy. A dashboard that leads with a love score has usually put the effect where the cause should be.
None of this is armchair theory. It has an applied home in the Ehrenberg-Bass Institute for Marketing Science in Adelaide, the research group, funded by corporate member companies, that turned Ehrenberg's empirical generalisations into working method, and whose translations for practitioners, Sharp's How Brands Grow and Romaniuk and Sharp's How Brands Grow Part 2, are where most marketers actually meet these laws (Sharp, 2010; Romaniuk and Sharp, 2016). The applied programme that falls out of it has three moves. First, budget for penetration: weight spend toward reaching the many light and occasional buyers who make up most of any brand's volume, and toward being physically easy to buy, rather than toward deepening the loyalty of the committed few. Second, audit and build distinctive assets. The colours, logos, characters, sounds, and shapes that make a brand instantly recognisable are measurable assets, and Romaniuk's Building Distinctive Brand Assets (Romaniuk, 2018) sets out the method: test each candidate asset for how many people link it to you (fame) and how few link it to anyone else (uniqueness), then invest in the ones that score on both and use them consistently. Third, research category entry points by frequency: map the cues, occasions, and needs that actually send people to buy, then rank them by how often they occur and how much buying they drive, so you build memory links to the handful that matter rather than a decorative list of forty (Romaniuk and Sharp, 2016).
The honesty edge here is mostly about not fooling yourself or your client. A loyalty narrative that is really a size effect, or a forty-point CEP audit that is really box-ticking, feels like insight and is not, and the audience test is simple: does the metric tell you something you could act on and be wrong about, or does it just flatter the brand? Hold the whole doctrine as a strong prior, not dogma, because in disrupted, fast-growth, subscription, or emerging markets the stationary-market laws bend, and there differentiation and retention can matter far more than the average says. The mature-market rules and the disruptive-edge exceptions are different games, and the applied skill is knowing which one you are in before you reach for the playbook.
The parallel to L5-01 is exact and worth drawing: just as campaign persuasion mostly reaches and reinforces rather than converts, party and cause advertising mostly keeps you mentally available and salient rather than arguing opponents into switching. Penetration thinking, broadening who considers you and being memorable at the moment of decision, tends to beat deep-loyalty thinking, lavishing attention on the committed base, for actual growth, with the standing caveat that in some systems the base is close to the whole game. The distinctive-asset lesson transfers cleanly too. The colours, symbols, slogans, and typefaces a movement owns are recognition assets worth auditing and using with discipline, because a voter who cannot instantly place who a message is from is a voter it did not reach. The equivalent of a category entry point is the issue or event that makes someone start paying attention, and being the name that comes to mind then is worth more than another appeal to people already decided. The physical-availability half transfers too: being easy to act on, a registration link that works, a nearby polling place, one clear next step, converts salience into behaviour, and a campaign strong on recall but weak on the mechanics of acting loses people who were already willing.
Public-service "brands", a health service, a benefit, an emergency number, a safety message, live or die on mental and physical availability far more than on affection: people use the option that comes to mind and is easy to reach at the moment of need. Being recall-able at the relevant category entry points ("I have lost my job", "my child is ill", "I want to quit smoking") and being genuinely easy to access does more than persuasive messaging aimed at building warm feeling. The distinctive-asset discipline applies with real public value: a consistent, recognisable identity for a crisis line or a public-health programme, held steady over years rather than rebranded each cycle, is what lets someone recall and trust it in the moment they need it. Consistency here is not blandness, it is the difference between being found and being missed. Physical availability matters as much as the mental kind: a service that is hard to reach, buried in a phone tree, open only in office hours, offered in one language, loses people at the exact moment of need however well it is recalled. Easy-to-find and easy-to-use is the public-sector version of easy-to-buy.
Three habits. Treat loyalty metrics with suspicion: before crediting devotion, ask whether the pattern is just double jeopardy, the size of the brand showing up as apparent loyalty. Optimise for being easy to remember and easy to buy, distinctive assets plus real, frequency-weighted category entry points, ahead of chasing love or differentiation for its own sake. And check the market before applying the laws: they are powerful priors for mature, stable categories and unreliable at the disrupted, fast-growing, or unfamiliar edges, so confirm you are in the world where they hold.
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