This article hasn’t been available on line for ages. Well here it is back again.
ABSTRACT
The objective of this paper is to throw some light on the issues of conceptualisation in brand loyalty research. Distinctions are made between three brand loyalty conceptualisations: attitudinal loyalty, repeat-purchase loyalty, and differentiation loyalty. The latter conceptualisation having received far less attention in the marketing (cf economic) literature on brand loyalty. This paper then details some recommendations for future research concerning the operationalisation of these concepts and exploring the relationships between each concept.
Key words: brand loyalty, customer loyalty, consumer loyalty
Marketing Science 
Any significant developments on this topic since 1997?
What is the actual marketing outcome that the “best” loyalty measure should correlate to most…market share…product profitability? How does the applied researcher help his company decide which “differentiation loyalty” measure to track?