The following paper discusses the analysis of some types of economic time series using an altered time scale, or … operational time. It is argued that for some series, observations that are ordinarily thought of as equidistant in time are … actually irregularly spaced in a more natural time scale. Section A discusses point or impulse sampling of related series and …

, while the time span of the data remains fixed, and the cross-sectional dimension is fixed or increasing. We derive a Central … Limit Theorem (CLT) for the cross-sectional beta dispersion at a point in time, enabling us to test whether this quantity … beta dispersion, as a function of time-of-day, changes across days. We extend this further by developing inference …

The canonical difference-in-differences (DD) model contains two time periods, "pre" and "post", and two groups … effects change over time. I propose a new balance test derived from a unified definition of common trends. I show how to … time fixed effects, control for unit-specific time trends, or exploit a third difference …

A significant amount of work time is lost each year due to worker absence, but evidence on the productivity losses from …

-- who invest in a risky asset until an exogenous but random termination time. In any time period they must invest all their …

, distress, payout policy, profitability, and industry. We consider interpretations of these results based on both time … exploit time-varying characteristic mispricing …