correlation
Hi, You need to plot the data before you can add an abline to it. Also, abline doesn't work with the raw data: you need to either supply coefficients or a regression. plot(SiO4,density) #plots the raw data abline(lm(density ~ SiO4)) # draws the regression line, for example Since you are interested in the *rank* relationship, you might want to use rank() on the data before plotting, and before lm(). Sarah
On Sun, Jan 8, 2012 at 11:41 AM, Mahnaz Rabbaniha <rab.mahnaz at gmail.com> wrote:
?Dear r-sig-ecology group,
I am trying to find correlation between two variables. whereas they are non-normal used Spearman in this way:
?cor.test(SiO4,density,method="spearman")
? ? ? ?Spearman's rank correlation rho data: ?SiO4 and density S = 5263.445, p-value = 0.1184 alternative hypothesis: true rho is not equal to 0 sample estimates: ? ? ?rho -0.296415
plot(SiO4, density)
but i cant draw the line and in others same files, the problem is same and what is meaning this message: library (graphics)
abline(density~SiO4)
Error in int_abline(a = a, b = b, h = h, v = v, untf = untf, ...) : ?plot.new has not been called yet .
Many thanks in advance, mahnaz
Sarah Goslee http://www.functionaldiversity.org