[R] Least Squares Fit

[Jonathan Baron]

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/