R Special Interest Group for the use of R in ecological and environmental data analysis

[R-sig-eco] Extracting information from lm results

Dear all,

I suspect that this might be a bit basic, but here goes anyway...

I am soon to run a large number of linear regressions and I would like to extract a number of details from the
models, and then collate them in a dataframe as a summary of the overall block of analyses. I can
successfully extract the intercept and slope by using, for example:

lm1<-lm(ASTF~Year,na.action=na.omit,subset=yr10==T)
a1<-lm1$coefficients[1]
b1<-lm1$coefficients[2]
out1<-cbind("ASTF","1996-2005",lm1$coefficients[1],lm1$coefficients[2])

However, I also would like to extract the following too:

1) the number of data points in the analysis, n
2) the standard error of the slope
3) the P value
4) the R-squared value

Is it possible to extract these parameters in the same way as the slope and intercept, to save a lot of typing?

Any help much appreciated!

Steve Thackeray

Dr Stephen Thackeray 
Lake Ecosystem Group
CEH Lancaster
Lancaster Environment Centre

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Ruben Roa Ureta | 2 May 17:29

Re: [R-sig-eco] Extracting information from lm results

> Dear all,
>
> I suspect that this might be a bit basic, but here goes anyway...
>
> I am soon to run a large number of linear regressions and I would like to
> extract a number of details from the models, and then collate them in a
> dataframe as a summary of the overall block of analyses. I can
> successfully extract the intercept and slope by using, for example:
>
> lm1<-lm(ASTF~Year,na.action=na.omit,subset=yr10==T)
> a1<-lm1$coefficients[1]
> b1<-lm1$coefficients[2]
> out1<-cbind("ASTF","1996-2005",lm1$coefficients[1],lm1$coefficients[2])
>
> However, I also would like to extract the following too:
>
> 1) the number of data points in the analysis, n

n <- length(ASTF)

> 2) the standard error of the slope

se.slope <- summary(lm1)[2,2]

> 3) the P value

p.v <- summary(lm1)[2,4]

> 4) the R-squared value

(Continue reading)

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Christoph Meyer | 2 May 11:06

Re: [R-sig-eco] Extracting information from lm results

Hi Steve,

you can extract this information from the summary of your linear
regressions, i.e. summary(lm1).

e.g.

sum.lm1=summary(lm1)
sum.lm1$coef[2,2]    #this gives you the SE of the slope
sum.lm1$r.squared    #this gives you the R2
and so on...
This should be clear from a look at str(sum.lm1).

Hope that helps,

Christoph

Friday, May 2, 2008, 9:55:10 AM, you wrote:

> Dear all,

> I suspect that this might be a bit basic, but here goes anyway...

> I am soon to run a large number of linear regressions and I would
> like to extract a number of details from the models, and then
> collate them in a dataframe as a summary of the overall block of
> analyses. I can successfully extract the intercept and slope by using, for example:

> lm1<-lm(ASTF~Year,na.action=na.omit,subset=yr10==T)
> a1<-lm1$coefficients[1]

(Continue reading)