Byron Sharp's Laws of Marketing

  1. Double jeopardy law: brands with less market share have fewer buyers who will be less loyal
  2. Retention double jeopardy law: Brands lose consumers in proportion to their market share
  3. Pareto’s law: More than half of a brand’s sales come from the top 20% of customers; the rest come from the bottom 80%.
  4. Law of buyer moderation: Heavy buyers’ consumption will decrease; light and non-buyers may increase purchasing toward the mean.
  5. Natural monopoly law: Brands with a larger market share have a more light buyers.
  6. Customer bases seldom vary. Competitors sell to the same customer bases.
  7. Attitudes reflect behavioural loyalty: Large brands score higher for loyalty because they have more users.
  8. Usage drives attitude: Buyers of different brands have similar attitudes and similar perceptions of different brands.
  9. Duplication of purchase law: Brand’s customer base will overlap rival brands’ in proportion to their market share
  10. Non-linear relationship between availability



Sharp, Byron. How Brands Grow: What Marketers Don’t Know. Illustrated edition. Oxford ; New York: Oxford University Press, 2010.