Recent protest movements brought attention to the one percent, a segment of the population that is critical to understanding inequality and social mobility but that attracts relatively little research attention. In this article, I survey current research on the one percent in the United States. I distinguish income from wealth and show that both are very concentrated but that the concentration ...

1.2 Machine failure A system is composed of 5 components, each of which is either working or broken. Consider an experiment that consists of observing the status of each component, and let the outcome of the experiment be given by the vector (x1, x2, x3, x4, x5), where xi = 1 if component i works and 0 if component i is broken. 1. How many outcomes are in the sample space of this experiment? 2....