great thanks a lot!

On Sat, Nov 6, 2010 at 3:54 PM, Kevin Middleton <kmm@csusb.edu> wrote:

>
> Eugenio -
>
> > I am confused with SMATR's test for common slope. My null hypothesis here
> is
> > that all slopes are parallel (common slopes?), right?
> > So if I get a p value < 0.05 means that we can have confidence to reject
> it?
> > That slopes are different?
> > Or the other way around? it means that we have statistical confidence
> that
> > the slopes are parallel?
>
> Try this:
>
> set.seed(5)
> n <- 20
> x <- rnorm(n)
>
> y1 <- 2 * x + rnorm(n)
> y2 <- 2 * x + rnorm(n)
> y3 <- 4 * x + rnorm(n)
>
> # Slopes approximately equal
> slope.com(x = c(x, x), y = c(y1, y2), groups = rep(c(1,2), each = n))
>
> #$p
> #[1] 0.4498037
>
> # Slopes of 2 and 4
> slope.com(x = c(x, x), y = c(y1, y3), groups = rep(c(1,2), each = n))
>
> #$p
> #[1] 0.0003850332
>
>
> Cheers,
> Kevin
>
> -------------------------------------------------
> Kevin M. Middleton
> Department of Biology
> California State University San Bernardino
>
>


-- 
Eugenio Larios
PhD Student
University of Arizona.
Ecology & Evolutionary Biology.
(520) 481-2263
elariosc@email.arizona.edu

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