When referring to segmentation most experienced researchers think of factor and cluster analysis. In conducting ad-hoc factor or cluster analysis a great deal of subjectivity (and creativity) flows into the 'equation' in terms of selecting the 'best' factors and cluster solutions for doctors or patient data. Hence the title of this paper 'Is this art or science?' The same question can be asked in a more concrete way: Is this (segmentation) subjective or objective? Like most things in life the answer is not black or white. There is a large grey area and most definitely our answer will be found there. No surprise here. You do not have to wait until you reach the end of this presentation to know the answer to the question: it is indeed a combination of art and science or a combination of subjectivity and objectivity. However the real issue here is how subjectivity can influence segmentation and by extension the marketing plan which in its turn affects the growth or success of the brand.