When an observer is confronted with a complex situation, it can be impossible
to observe many different individuals and record many different behaviors
simultaneously. One solution is to record the situation so the scene
can be replayed repeatedly to gather observations. A second solution is to
take a sample of the potential observations rather than attempt to watch
and record everything. The first step in the process of sampling observations
is to divide the observation period into a series of time intervals. The
sampling process then consists of one of the following three procedures: