User`s guide

Smoothing Data
2-23
Use the Plotting GUI to display only the data sets of interest. As shown below,
the periodic structure of the ENSO data set becomes apparent when it is
smoothed using a moving average filter with the default span. Not
surprisingly, the uncovered structure is periodic, which suggests that a
reasonable parametric model should include trigonometric functions.
Refer to “General Equation: Fourier Series Fit” on page 3-52 for an example
that fits the ENSO data using a sum of sine and cosine functions.
Display only the data set
created with the moving
average method.
The smoothing process
uncovers obvious periodic
structure in the data.