Ehrenberg-Bass Laws

Also known as: How Brands Grow

framework · marketing · organizing-schema

Empirical regularities in buying behavior, including double jeopardy and brand penetration.

The Ehrenberg-Bass Laws are the body of empirically-derived regularities in consumer purchasing behavior identified through decades of research at the Ehrenberg-Bass Institute (formerly the Marketing Science Centre at the University of South Australia), founded by Andrew Ehrenberg and substantially developed by Byron Sharp. The framework is grounded in unusually rigorous empirical analysis of consumer-panel data across hundreds of categories, brands, and countries. Key empirical regularities include: (1) Double Jeopardy — small brands have fewer customers AND those customers buy slightly less often (challenging segmentation-and-positioning thinking that small brands can compete through loyalty); (2) Duplication of Purchase Law — brands share customers in proportion to brand size, not in proportion to similarity (challenging segmentation thinking); (3) Negative Binomial Distribution (NBD) of purchases — purchase patterns follow predictable mathematical distributions; (4) Light buyers dominate sales — the bulk of any brand's sales come from many occasional buyers, not from few heavy loyal buyers (challenging loyalty-program economics); (5) Penetration drives growth, not loyalty — brands grow primarily by acquiring more customers, not by getting existing customers to buy more. Byron Sharp's How Brands Grow (2010, with Volume 2 in 2016 with Jenni Romaniuk) substantially popularized the framework. Ehrenberg-Bass research challenges substantial parts of the dominant marketing tradition — STP positioning, loyalty programs, segmentation strategies, brand-purpose marketing, and customer-relationship marketing all face empirical pushback from this work. The framework is unusually well-supported empirically by marketing-research standards but has been controversial precisely because its findings challenge what most marketers do.

Originators

Andrew S. C. Ehrenberg (foundational, mid-20th century onward); Byron Sharp (substantial contemporary development and popularization); Jenni Romaniuk (subsequent development); broader Ehrenberg-Bass Institute research community high

Year / Decade

Ehrenberg's work mid-20th century onward; 2010 (Sharp's How Brands Grow); 2016 (How Brands Grow Volume 2); ongoing institutional research high

Primary sources

Sharp, B. (2010). How Brands Grow: What Marketers Don't Know, Sharp, B. & Romaniuk, J. (2016). How Brands Grow: Part 2, Ehrenberg, A.S.C. (1959, 1988). Repeat-Buying: Theory and Applications, Ehrenberg-Bass Institute publications (ongoing) high

Core components

Double Jeopardy (small brands have fewer customers who buy slightly less often)
Duplication of Purchase Law (brands share customers proportional to size, not similarity)
Negative Binomial Distribution of purchases
Light buyers dominate sales
Penetration drives growth more than loyalty
Mental and Physical Availability as key brand-growth drivers
Distinctive Assets (rather than positioning differentiation)
Empirically-derived rather than theoretically-deduced
Challenges to STP, loyalty programs, segmentation, brand-purpose marketing
Substantial cross-category and cross-country empirical support

Primary use case

Brand-growth strategy; foundation for empirically-grounded marketing strategy alternative to STP-based approaches; reference framework in advertising effectiveness research (substantial influence in agencies including BBDO, Anomaly, others); basis for substantial marketing-science research; integration with marketing-mix modeling and econometrics; growing influence in CMO communities seeking empirical foundations; pedagogical framework in marketing-science education programs.

Common criticisms

Specific findings are robust empirically but the strategic prescriptions Sharp draws from them are more contested — critics including Mark Ritson, Peter Field, and Les Binet (the latter two from a different empirical tradition with the IPA databank) argue Ehrenberg-Bass underweights long-term brand-building effects of differentiation and emotional positioning
the framework's pushback against STP and segmentation has been argued to be overstated — some segmentation works even if the bulk of sales comes from broad-market light buyers
works better for low-involvement frequent-purchase categories (FMCG, beverages) than for high-involvement infrequent-purchase categories (cars, financial services)
B2B applications are limited by data availability
substantial intra-marketing-science debate continues about the relationship between Ehrenberg-Bass findings and earlier marketing traditions
commercial application sometimes oversimplifies the empirical claims into 'just maximize reach and availability'
the framework's empirical rigor has produced confidence that occasionally outpaces specific findings' generalizability.

Lineage

Siblings: STP, 4Ps of Marketing