Hi, Are there any special statistical tests, or functions in R I could use to measure "cone-like" distributions? I have several data-sets, which I've been plotting parts of as 2D plots, where I get a "cone-like" distribution of the data points. That is, the data appears to be bounded by two non-parallel lines, starting at the origin, giving rise to a "cone-like" appearance. I guess I could work out it's bounding lines fairly easily, but this seems perhaps a fairly naive thing to do, and I was wondering if there are any standard tests to do? I guess one might consider the angle of the cone, how much of the "cone" is filled out, density of points within the cone and so on. I don't even know if thinking of a "cone" makes any sense, what it would mean or whether I should simply be thinking of a linear regression line with some non-constant variance? An example plot is at http://cs.swan.ac.uk/~csmg/aes/plots/canon_1_3_4_r1_v_cfs.pdf if anyone is interested. Thanks in advance! Matthew Gwynne http://cs.swan.ac.uk/~csmg/
Statistical tests and measures for "cone-like" distributions?
3 messages · Matthew Gwynne, Albyn Jones, Ben Bolker
Have you tried plotting log(y) vs log(x)? albyn
On Wed, Dec 21, 2011 at 02:18:56PM +0000, Matthew Gwynne wrote:
Hi, Are there any special statistical tests, or functions in R I could use to measure "cone-like" distributions? I have several data-sets, which I've been plotting parts of as 2D plots, where I get a "cone-like" distribution of the data points. That is, the data appears to be bounded by two non-parallel lines, starting at the origin, giving rise to a "cone-like" appearance. I guess I could work out it's bounding lines fairly easily, but this seems perhaps a fairly naive thing to do, and I was wondering if there are any standard tests to do? I guess one might consider the angle of the cone, how much of the "cone" is filled out, density of points within the cone and so on. I don't even know if thinking of a "cone" makes any sense, what it would mean or whether I should simply be thinking of a linear regression line with some non-constant variance? An example plot is at http://cs.swan.ac.uk/~csmg/aes/plots/canon_1_3_4_r1_v_cfs.pdf if anyone is interested. Thanks in advance! Matthew Gwynne http://cs.swan.ac.uk/~csmg/
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Albyn Jones Reed College jones at reed.edu
Matthew Gwynne <mathew.gwynne <at> gmail.com> writes:
Hi, Are there any special statistical tests, or functions in R I could use to measure "cone-like" distributions? I have several data-sets, which I've been plotting parts of as 2D plots, where I get a "cone-like" distribution of the data points. That is, the data appears to be bounded by two non-parallel lines, starting at the origin, giving rise to a "cone-like" appearance.
You may be interested in quantile regression. Roger Koenker, who has developed a lot of the basic methodology for quantile regression, is also the author of the quantreg package (which comes with a fairly thorough vignette IIRC).