Hi everyone, I am not sure this is the appropriate list I should put this question to, but I hope you will re-direct me to the most appropriate one if necessary.
I am doing an independent component analysis on a dataset that represents different metrics for patchreefs such as depth, area, volume, relative relief, shape index and rugosity. Doing different multivariate analyses and correlations among variables we discovered that the average reef depth data is heavily bi-modal, and rugosity behaves differently in each of the depth populations. Other reef metrics behave differently with depth as well. Since not all metrics are really independent we did a PCA analysis followed by cluster analysis and we tried to compare the results with the results from the depth analysis. It was not too conclusive I am afraid, and trying to understand the results I came across independent component analysis (ICA). So ?.. I?ve run it on a combination of principal components and it seems that certainly we have 2 independent components that keep popping up (if I can use this expression) when we run the analysis with 2, 3, or 4 components. So I guess these 2 components are the strongest ones ?. If I can say so. My next question is ?. How can I relate these 2 components to the initial data??? I?ve plotted each component and if I add a loess line to each, visually it seems that one independent component is an unknown function of rugosity while the other component is an unknown function of reef geometry and depth. But, of course, I would like something more than a visual similarity. Also the 2 independent components seem to split the data in 3 classes, rather than 2, as the analysis of the depth data suggested. Looking back at the depth histogram it is obvious that there are some data that actually are not quite modeled by the 2 mixing functions I came up with. These data correspond to the deepest patch reefs, a category clearly singled out by ICA classification. The bottom line is that I am trying to understand what each independent component tells me about the patch reefs and how I can relate that to the patch reef morphometrics, biology, other factors that impact some reefs but not others, etc. If you have any clarifying thoughts or if you know about any other literature about the subject that can help (except articles that deal with ICA and image analysis or wave form data) I will really appreciate. Thank you very much for your consideration, Monica ==================================== Monica Palaseanu-Lovejoy ETI / US Geological Survey Florida Integrated Science Center 600 4th Street South St. Petersburg, FL 33701 Ph: 727-803-8747 x 3068 Fx: 727-803-2031 email: [EMAIL PROTECTED] ====================================
