Message-ID: <CAM_vju=Nop1bECamCnryWdMJYyxCMWC6c3R0Qutm4k2FaQt3bA@mail.gmail.com>
Date: 2012-01-08T17:07:42Z
From: Sarah Goslee
Subject: correlation
In-Reply-To: <CANLCanWX-+XMpMJ5UhHo3ffP8RPjYM8ZehWBN7Xw4Ddhv7hG4A@mail.gmail.com>
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