Imagine a disease cluster. Does the cluster have a certain shape? Does the cluster have a certain size? Where is this disease cluster? What disease did you choose? The subjectivity of what defines a cluster is an area of surprising ambiguity. Nevertheless, cluster methodologies are routinely used by academics, corporations, and the government as a decision-making tool. In this video, we explore the ambiguity of what defines a cluster and how that ambiguity presents potential ethical dilemmas.