We have a number of tools for looking at time series and searching for periodicity in the data. The Nyquist Sampling Theorem relates the frequency at which you sample the time series to the frequencies in the original data series that you can resolve.
We will consider a time series to be a sequence of readings of some parameter at equally spaced points in time, although in many cases we could also consider a series of equally spaced values of the parameter along a horizontal distance axis. Waves represent time series that we can visualize either on a time or distance axis: on a time axis we remain at a fixed point and see how the water surface varies at discrete points in time, and on a distance axis we freeze the water surface and see how the surface varies at discrete distances along it. Tides represent time series that we can visualize on a time axis: we remain at a fixed point and see how the water surface varies at discrete points in time.
We look at time series for two reasons:
If we had clean data this would be an easy process, but real world data can be very noisy and we need mathematical assistance.
Methods in MICRODEM for looking at time series available on Stats button of table display window for a database.
Last revised 2/21/2016