[R] Quantitative analysis of non-standard scatter plots.

From: Firas Swidan <frsswdn_at_gmail.com>
Date: Wed, 23 Jul 2008 16:07:43 +0300


I am having difficulties in finding ways to analyse scatter plots and quantitatively differentiate between them. Since this is best demonstrated by a figure, I have attached one with 4 subfigures (a)-(d). Qualitatively
(and I hope you would agree with me), sub-figures (a), (b), and (d) seem to
represent uniform 2d scatters. It is hard for me to quantify it, but it seems as if the envelopes (max values of y-axis) are independent of the values of the x-axis. Sub-figure (c), on the other hand, exhibits a different behaviour, as the envelope seems to expand as the x-values increase (at least till some threshold, and with the exception of a single outlier toward the begining of the x-axis). My question is how can I verify the above observation quantitatively, and does R provide the required tools for doing so? I have tried to perform linear fittings and to claim that the slope of the fitted line in (c) is more significant than the lines in (a),
(b), and (d), but this does not seem convincing to me. Are there standard
toolboxes for such cases?

Thanks for any suggestions / tips,

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Received on Wed 23 Jul 2008 - 13:34:29 GMT

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