The book demonstrates the variety of situations where noise is present and yet ignored, despite undeniable evidence of the damage it causes. In showing how noise wreaks havoc in situations where most people unanimously agree that it should not be present, such as across prison sentences for the same crime or in the diagnosis of a patient, the authors make a strong case for treating noise as “an invisible enemy” and waging a war against it (284). The authors acknowledge that the invisibility of noise, especially compared to the more visceral, status-quo-enforcing distractor known as bias, makes it difficult to identify. Indeed, level noise, which can be defined as a consistent tendency in a particular person or institution, has much in common with bias. However, while bias is often focused on a single faulty premise, noise arises in a scattered way, analogous to the authors’ example of a team at the shooting gallery whose shots diverge from the bull’s eye at all different angles. Variance in judgment is a problem when people get treated differently in the same circumstance, and in extreme cases this can cause preventable loss of life or opportunity.