[R] Formatting multi-way ANOVA output for spectra analysis
Robert D. Bowers M.A.
n4fbz @ending from t@mp@b@y@rr@com
Wed Jul 25 19:11:55 CEST 2018
I've studied R a little bit, although I haven't used it in some time
(except via RCommander). I'm working on my dissertation project and
have spectrometer data that I need to evaluate. I need to find a way to
simplify the output from multi-way ANOVA so I can reduce the areas of
the spectrum to only those where there are significant differences
between sites. (A preliminary study on a too-small sample size
indicates that certain areas of the spectrum can distinguish between
sites. This project is the next step.)
The dataset is comprised of analyses done on samples from five separate
locations, with 50 samples taken from each site. The output of the
spectrometer per sample is values for 2048 individual wavelengths, in a
spreadsheet with the wavelength as the first column. Since I'm doing
the analysis wavelength-by-wavelength, I've transposed the data and
broke the data for the project down into smaller spreadsheets (so that R
can perform ANOVA on each wavelength).
The problem is, I can do ANOVA now on each wavelength, but I don't need
a full output table for each... I just need to know if there is
significant variation between any of the sites at that wavelength, based
on 95% confidence level (or better). If I could get some sort of simple
chart (or a single line in a spreadsheet), that would help to narrow
down the areas of the spectrum that I need to focus on to evaluate the
results of the tests.
I've been reading information about ANOVA, but have found very little
that is clear about formatting the output - and I don't need to rehash
all of the math. I just need to find out how to hack down the output to
just the part I need (if possible). Once that's done, I can decide what
wavelengths are valuable for future tests and simplify the process.
Thanks for any help given!
Bob
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