Message-ID: <20030225063036.A27568@cattell.psych.upenn.edu>
Date: 2003-02-25T12:32:04Z
From: Jonathan Baron
Subject: linear trend
In-Reply-To: <3E5B51DA.5ABF38F9@giub.unibe.ch>; from rutis@giub.unibe.ch on Tue, Feb 25, 2003 at 12:22:02PM +0100
On 02/25/03 12:22, This Rutishauser wrote:
>can anyone help me with a hint how to find a function to fit a linear
>trend line into a scatter plot. as well as testing it for significance.
Look at the help page for abline(). That is what you use for
drawing lines in a plot. It turns out that you can specify the
line with lm(), and summary(lm()) gives you the significance
test. For example (all but the last line from ?abline):
data(cars)
z <- lm(dist ~ speed, data = cars)
plot(cars)
abline(z)
summary(z)
--
Jonathan Baron, Professor of Psychology, University of Pennsylvania
R page: http://finzi.psych.upenn.edu/