Time series showing seasonality- marked variation with time of year- are of interest to many scientists, including climatologists, other environmental scientists, epidemiologists, and economists. The usual graphs plotting response variables against time, or even time of year, are not always the...

Many problems in statistical analysis include time-of-day variables, but Stata offers limited support for time-of-day calculations. Support is needed for dates with times, times alone, and durations or timings. This article presents two new programs as general utilities to convert back and forth...

Spells in time series (and more generally in any kind of one-dimensional series) may be defined as sequences of observations that are homogeneous in some sense. For example, a categorical variable may remain in the same state, or values of a measured variable may satisfy the same true-false...