Social scientists are often interested in measuring time devoted to different activities over some reference period such as weeks worked for pay in a year, or hours per day spent in housework or childcare. Besides the elapsed time in a certain domain, they may also want some characterization of the activity, such as attributes of a spell of time or information on the timing of external events or transitions from one activity or state to another. The purpose of such measures is to construct variables which capture the level of designated time allocations and responses for the purpose of understanding behavior in the context of a model. In turn, the model portrays the choices of individuals with respect to a type of behavior, ranging from work, leisure, health states and investment (Juster 1985; Juster & Stafford 1991; Gershuny 2000) to episodes of violence or periods in various affective states. In such analyses a goal can be to understand factors shaping well-being. The extent and nature of the economic model is a major issue. [PUBLICATION ABSTRACT]