simple test on slope of lm()
Hello, To test the slope of your linear model against an arbitrary value, you can use lm() directly with a little trick. Let b1 be the value of the slope you want to test your model against, then use lm(y-b1*x~x). The significance test of the slope for this lm model gives the answer you need. > x <- rnorm(10) > y <- 2*x + rnorm(10) > lm(y~x) > lm(y-2*x~x) Hope this helped, Yves Brostaux.
At 04:01 23/11/02, you wrote:
Date: Fri, 22 Nov 2002 22:08:43 +0100 From: Fred JEAN <frederic.jean at univ-brest.fr> Subject: [R] simple test on slope of lm() Hello I want to compare the slope (let's say 'b') of a linear model obtained with lm() to a theoretical value (let's say 'th'). To do so, I think I should compute a 't value' using something like : (b - 'th')/standard.deviation(b) and then look at the p-value of this computed t. I don't understand how to do this in a simple way, just using lm() outputs for example. I'm sorry of such a naive/newbie question, and thank you so much for taking time to answer. Fred
Ir. Yves Brostaux - Statistics and Computer Science Dpt. Gembloux Agricultural University 8, avenue de la Facult? B-5030 Gembloux (Belgium) T?l : +32 (0)81 62 24 69 E-mail : brostaux.y at fsagx.ac.be Web : http://www.fsagx.ac.be/si/ -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html Send "info", "help", or "[un]subscribe" (in the "body", not the subject !) To: r-help-request at stat.math.ethz.ch _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._