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ARS Home » Midwest Area » Ames, Iowa » National Laboratory for Agriculture and The Environment » Agroecosystems Management Research » Research » Publications at this Location » Publication #219184
Title: D02: Graphs to aid in spectral analysis

Author
item Meek, David

Submitted to: Midwest SAS Users Group Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 7/25/2007
Publication Date: 10/30/2007
Citation: Meek, D.W. 2007. D02: graphs to aid in spectral analysis [CD-ROM]. In: Data Visualization and Graphics Section, Midwest SAS Users Group Annual Conference Program Book, October 28-30, 2007, Des Moines, IA.

Interpretive Summary:

Technical Abstract: This paper is intended for those familiar with the discrete Fourier transform and PROC SPECTRA from SAS/ETS®. The procedure is called through a macro and the output variables are used to develop three diagnostic graphs and a montage. The first graph displays the log10 of the spectra, a Hanning weight interpolation of the spectra, and the 95% confidence bands of the spectra as a function of the log10 of the frequency. The second graph is an overlay of two related plots. The first plot displays the spectral density as a function of the wave number. The values are represented by black points with the ordinates plotted using the black left-hand vertical axis scale. The second plot displays the periodgram fraction as a function of the wave number. The values are represented by gray-scale needles with the ordinates plotted using the gray right-hand vertical axis scale. The third graph displays the normalized cumulative periodgram including the 95% confidence limits as a function of the wave number. A table with spectral tests is also presented. The sun spot record from 1700 -1991 is used to generate an example set of graphs and a table.