[R] Bad points in regression

[Petr Pikal]

Hi

you can check ?influence  or ?influence.measures to evaluate some 
regression diagnostics

Regards
Petr


On 16 Mar 2007 at 9:56, Alberto Monteiro wrote:

From:           	"Alberto Monteiro" <albmont at centroin.com.br>
To:             	r-help at stat.math.ethz.ch
Date sent:      	Fri, 16 Mar 2007 09:56:56 -0200
Subject:        	[R] Bad points in regression

> I have a question, maybe it's better to explain by example:
> 
> alpha <- 0.3
> beta <- 0.4
> sigma <- 0.5
> err <- rnorm(100)
> err[15] <- 5; err[25] <- -4; err[50] <- 10
> x <- 1:100
> y <- alpha + beta * x + sigma * err
> ll <- lm(y ~ x)
> plot(ll)
> 
> Now, the graphs clearly show that 15, 25 and 50 are the indexes
> of the bad points. How can I retrieve this information from ll?
> 
> Alberto Monteiro
> 
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Petr Pikal
petr.pikal at precheza.cz