[R] Accessing specific values of linear regression model

Liaw, Andy andy_liaw at merck.com
Thu Mar 23 20:56:26 CET 2006


You said you were fitting regression model, yet you used
summary(aov(model))?  It's rather unusual to use aov() for regression
models...

If you used lm() to fit the regression model, the following might help:

> y <- rnorm(10); x <- runif(10)
> fit <- lm(y ~ x)
> anova(fit)
Analysis of Variance Table

Response: y
          Df Sum Sq Mean Sq F value Pr(>F)
x          1 1.2526  1.2526  1.6872 0.2302
Residuals  8 5.9397  0.7425               
> str(anova(fit))
Classes anova  and `data.frame':        2 obs. of  5 variables:
 $ Df     : int  1 8
 $ Sum Sq : num  1.25 5.94
 $ Mean Sq: num  1.253 0.742
 $ F value: num  1.69   NA
 $ Pr(>F) : num  0.23   NA
 - attr(*, "heading")= chr  "Analysis of Variance Table\n" "Response: y"
> anova(fit)["x", "Sum Sq"]
[1] 1.252643

Andy


From: Kelly Vincent
> 
> I am just starting to learn R, and I'm struggling with a lot 
> of the basic 
> stuff. The online documentation is generally good, but I have 
> been unable to 
> find the answer for my problem this time.
> 
> I am running linear regression on a particular set of data 
> and plotting it. 
> I've got the regression line plotted and everything is fine 
> so far, except 
> for one thing: I want to display the SSE from the regression 
> and I don't 
> know how to access it. In my script I have:
> model <- lm(y~x)
> and I was able to get the r^2 value that I wanted with: 
> summary(model)$r.squared But I don't know how to get the SSE. 
> When I print the summary(aov(model)) I 
> get the following:
>             Df  Sum Sq Mean Sq F value    Pr(>F)
> x            1 1793928 1793928  67.463 3.447e-11 ***
> Residuals   56 1489118   26591
> ---
> Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
> 
> So it's there (I can see it!) but how do I get to it? Any 
> help would be much 
> appreciated.
> 
> Thanks,
> Kelly
> 
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