To understand the relation between environmental variables (such as phytoplankton, nutrients, salinity, suspended matter), many people used to use PCA and CCA plots. For my data I would like to use this type of graphical representation for conveying my results. Can anyone help me on how to make those plots and how to understand those graphs also? And, which software can we use to plot those graphs?
Priciple Component Analysis (PCA) is a chemometric method to separate compounds, is a multivariate analysis of data. You can use to check if the variables are related or not in MatLab, Pirouette, etc. At first you have to build a matrix, which lines are samples and column are variables. If your variables have different scales, you choose autoscale the data. And them, you plot loadings (variables contribution) to see relations.
PCA is arguably the most common multivariate chemometrics method and it would be hard to find a chemometrics software package that doesn’t include it. Many of these packages are very expensive or may require extensive training to use. However there are several packages that work within Excel that I have found from a brief Google search:
· moderately priced software Pro Core statistical software including PCA/CA and many other chemometrics, data processing, visualisation , etc. tools, working with any Excel version from Excel 97 and
· freeware from Numerical Dynamics also containing PCA but with a much smaller range of features, and only working with Excel 2007 or later.
Both of these packages include visualisation tools
I have added the links to these two pages below. I hope this information is useful to you.
http://www.xlstat.com/en/products-solutions/pro.html
http://www.numericaldynamics.com/index.html
Also is possible to PAST software for you calculations. It is also free and very simple in use.
http://folk.uio.no/ohammer/past/
I have also used PAST. I can highly recommend it. The outputs can be saved as JPEGS.
Dear Bharathi,
You may take software either form Dr.Sridevi or Mr. Sujit Kumar.
Murty
As I know, many software can be utilized to conduct PCA or CCA analysis, including SPSS, SAS and R, to name but a few.
PAST is a very easy software to use, and the PCA biplots it produces are very informative and easily editable.
Gretl is very easy to use siftware and it performs PCA with results that is easily underatandable
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