[R] Formatting multi-way ANOVA output for spectra analysis

[Fox, John]

Dear Robert,

Although you don't say so, it sounds as if you may be using the Anova() function in the car package, which is what the R Commander uses for ANOVA. If so, in most cases, Anova() returns an object of class c("anova", "data.frame"), which can be manipulated as a data frame. To see this, try something like

str(Anova(your.model))

You should be able to extract, manipulate, and graph whatever components of the object interest you.

I hope this helps,
 John

-----------------------------------------------------------------
John Fox
Professor Emeritus
McMaster University
Hamilton, Ontario, Canada
Web: https://socialsciences.mcmaster.ca/jfox/



> -----Original Message-----
> From: R-help [mailto:r-help-bounces using r-project.org] On Behalf Of Robert D.
> Bowers M.A.
> Sent: Wednesday, July 25, 2018 1:12 PM
> To: r-help using r-project.org
> Subject: [R] Formatting multi-way ANOVA output for spectra analysis
> 
> 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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