A classification of time series

We end this section with a brief classification of time series data. Although it is useful to recognise the different types of time series, all are analysed with the same statistical techniques (at least at introductory level).

Time series data arise in various different contexts.

Measurements relating to events that occur at discrete times
e.g. the dividend paid out each year on British Airways shares
Regular snapshots of a continuous process
e.g. the Consumer Price Index at the end of each month
Quantities that are aggregated over a period
e.g. the numbers of admissions to a hospital each day, or monthly energy consumption

Further, the measurements themselves may be of various different types.

Continuous
e.g. fat content in homogenised milk produced by a bottling factory
Discrete
e.g. number of complaints received by a department store each day

As mentioned earlier, we do not need to further distinguish between the different types of time series at this level of course.