To understand error in judgment, we must understand both bias and noise. Bias has been discussed in thousands of scientific articles and dozens of popular books, but few mention the problem of noise. In fact, noise can be the more important problem, but most of the time, individuals and organizations alike are unaware of it or neglect it. What is noise and how do you measure it in judgment and decision making? With a few simple remedies, people can reduce both noise and bias, and make far better decisions.