Double Jeopardy - 50 years on. Reviving a forgotten tool that still predicts brand loyalty

Scientific knowledge builds by continuously subjecting its known laws to differentiated replication. Empirical generalisations capturing the Law of Double Jeopardy have been extensively tested in this way for decades, and rightly so because they continue to provide a valuable managerial key to the multi-million dollar question of how brands grow. This research continues that work, first by extending knowledge of the operation of Double Jeopardy in the less familiar conditions of long-run continuous buying, emerging markets, capital purchasing and house of brand strategies, and second by validating the rather overlooked w(1- b) approximation as a simple tool with which to predict behavioural brand loyalty. Observations of competitive brand performance in 32 differentiated replications, some over thirty five years apart, find no boundary condition to the operation of the Double Jeopardy characteristic even in contexts that might initially suggest a challenge to its independence assumptions. We outline the implications for managers in these new findings in terms of insight, planning and brand audit.