R help - May 2004 - Least Squares Fit

Hello

I need to plot the least squares fit and get the slope
of the line that best fit the data. after reading lm
and lsfit, since not being able to understand the use
of the second argument "y" for the lsfit, I am giving
the lm a go, but know not why the code below does not
draw the line on the plot. e.g. well.. why -50
Intercept?
thanks

x <- 1:10; y <- x+50
plot(x,y)
z <- lm(as.data.frame(cbind(x,y))))
abline(z)
> z$coefficients
(Intercept)           y 
        -50           1

On 05/02/04 03:26, Fred J. wrote:
>Hello
>
>I need to plot the least squares fit and get the slope
>of the line that best fit the data. after reading lm
>and lsfit, since not being able to understand the use
>of the second argument "y" for the lsfit, I am giving
>the lm a go, but know not why the code below does not
>draw the line on the plot. e.g. well.. why -50
>Intercept?
>thanks
>
>x <- 1:10; y <- x+50
>plot(x,y)
>z <- lm(as.data.frame(cbind(x,y))))
>abline(z)
>
>> z$coefficients
>(Intercept)           y
>        -50           1
The lm() is predicting x from y, and plot() is plotting y as a
function of x.

Try
plot(x,y)
abline(lm(y~x))

-- 
Jonathan Baron, Professor of Psychology, University of Pennsylvania
Home page:            http://www.sas.upenn.edu/~baron
R page:               http://finzi.psych.upenn.edu/