Double jeopardy is an empirical law in marketing

Marketing

Marketing is the process used to determine what products or services may be of interest to customers, and the strategy to use in sales, communications and business development. It generates the strategy that underlies sales techniques, business communication, and business developments...

 where, with few exceptions, the lower market share brands in a market have both far fewer buyers in a time period and also lower brand loyalty

Brand loyalty

The American Marketing Association defines brand loyalty as:# The situation in which a consumer generally buys the same manufacturer-originated product or service repeatedly over time rather than buying from multiple suppliers within the category .# The degree to which a consumer consistently...

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The term was originally coined by social scientist William McPhee in 1963 who observed the phenomenon, first in awareness and liking scores for Hollywood actors, and later in behaviours (e.g. reading of comic strips and listening to radio presenters). Shortly afterwards Andrew Ehrenberg discovered the Double Jeopardy law generalised to brand purchasing. Subsequently Double Jeopardy has been shown to apply across categories as diverse as laundry detergent to aviation fuel, across countries and time.

This empirical

Empirical

The word empirical denotes information gained by means of observation or experimentation. Empirical data are data produced by an experiment or observation....

 law-like phenomenon is due to a statistical selection effect that occurs if brands are broadly substitutable selling to much of the same types of people (often referred to as a lack of Product differentiation

Product differentiation

In economics and marketing, product differentiation is the process of distinguishing a product or offering from others, to make it more attractive to a particular target market. This involves differentiating it from competitors' products as well as a firm's own product offerings...

 and market partitioning). The Double Jeopardy empirical generalization is explained and predicted by the NBD-Dirichlet theory of repeat purchase.

Marketing strategy implications

The main implication of Double Jeopardy is that market share growth depends substantially on growing the size of a brand's customer base.

So brand managers of a smaller market share brand should not be reprimanded for lower customer loyalty metrics. Also, they should not be expected to build customer loyalty to the brand without substantially increasing the brand's market penetration.

Exceptions to double jeopardy

There are two potential deviations from Double Jeopardy, (1) a brand with unusually low penetration and consequently higher loyalty constituting its market share (known as a niche brand), and (2) unusually high penetration and low repeat-purchase rates (known as a change-of-pace brand). Known examples include:

• retailer brands (store brands) - niched because of their restricted distribution these brands' market share is constituted of low penetration and consequently unusually repeat buying.
• Hispanic TV networks in the USA - niched because most US viewers do not speak Spanish these networks have few viewers but these fewer (Spanish speaking) viewers watch for an unusually high number of hours compared to viewers of similarly rating networks.
• seasonal brands (e.g. chocolate Easter eggs) - for their respective market shares these brands have an unusually high penetration and low repeat-purchase rates (i.e. they are change-of-pace brands).