Class certification and class actions revolve around key statistical issues: numerosity, commonality, and predominance. In addition, the plaintiff must demonstrate the ability to calculate damages for the class. Numerosity is not an issue that is contested frequently, but commonality is a focus point in a number of cases. How (or whether) one defines a population and demonstrates common characteristics and common harm can be crucial to the determination of whether a class is certified. Tied to commonality is the ability to calculate damages for the class and whether it is possible to allocate damages to individual members of the class. If the class itself is indeterminate, then one has to question how damages are determined.
We consider the issues using statistical tools and examine the theoretical issues regarding how the damage occurred. We help determine whether a class can be defined and, if so, how it can be defined.
