During the last decades, shared decision making (SDM) has become a very popular model for the physician-patient relationship. SDM can refer to a process (making a decision in a shared way) and a product (making a shared decision). In the literature, by far most attention is devoted to the process. In this paper, I investigate the product, wondering what is involved by a medical decision being shared. I argue that the degree to which a decision to implement a medical alternative (...) is shared should be determined by taking into account six considerations: (i) how the physician and the patient rank that alternative, (ii) the individual preference scores the physician and the patient (would) assign to that alternative, (iii) the similarity of the preference scores, (iv) the similarity of the rankings, (v) the total concession size, and (vi) the similarity of the concession sizes. I explain why shared medical decisions are valuable, and sketch implications of the analysis for the physician-patient relationship. (shrink)