1. A method of evaluating client status, comprising: receiving client data representing events from a set of different event types performed by clients, wherein the clients are in a non-contractual setting with a firm offering products or services to the clients; estimating, using a computer and based on the client data, parameters of a statistical model that describes client behavior, wherein a churn type of event is encoded in the statistical model as an absorbing state of a stochastic process, with a time of transition to the absorbing state modeled as being infinite, wherein the churn type of event is not observable in the client data, and performance of the churn type of event places the clients in a permanently inactive condition with the firm, and wherein at least one of the parameters corresponds to the churn type of event; calculating a likelihood of churn for a plurality of the clients at one or more time points using the statistical model and its estimated parameters; and selecting a client for which the likelihood of churn meets a predefined condition, the client selected to remain active with the firm.