[R] Q: extracting data from lm

[Chuck Cleland]

D. R. Evans wrote:
> Warning: I am a complete newbie to R. I have read ISwR, but I am still
> finding myself completely stuck on some simple concepts.
> 
> I have tried everything I can think of to solve this one, and finally
> decided that enough was enough and I need a pointer to a solution.
> 
> I have the following summary from lm():
> 
> ----
> 
>> summary(lm(nu1~nu4))
> 
> Call:
> lm(formula = nu1 ~ nu4)
> 
> Residuals:
>      Min       1Q   Median       3Q      Max
> -1572.62  -150.38   -21.70   168.57  2187.84
> 
> Coefficients:
>             Estimate Std. Error t value Pr(>|t|)
> (Intercept) 29.88739   43.68881   0.684    0.494
> nu4          1.00036    0.01025  97.599   <2e-16 ***
> ---
> Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1
> 
> Residual standard error: 470.9 on 298 degrees of freedom
> Multiple R-Squared: 0.9697,     Adjusted R-squared: 0.9696
> F-statistic:  9526 on 1 and 298 DF,  p-value: < 2.2e-16
> 
> ----
> 
> But I want to access some of these numbers programmatically. I finally
> figured out that to get the estimate of the nu4 coefficient I need to do:
> 
> ----
> 
>> lm(nu1~nu4)$coefficients[2]
>      nu4
> 1.000363
> 
> ----
> 
> which to me as a long-time C++ programmer is close to black magic (I've
> been programming since 1972; I have to say that R is unlike anything I've
> ever seen, and it's far from trivial to get my head around some of it --
> for example, how I could have known a priori that the above is the way to
> get the nu4 coefficient is beyond me). Anyway, having figured out how to
> get the estimate of the coefficient, I not-unnaturally wanted also to find
> a way to access the std. error of the estimate (the value 0.01025 in the
> summary). But I am completely mystified as to how to do it :-(
> 
> Any help gratefully (VERY gratefully) received, and I apologise if this is
> a really, really stupid question and that the answer lies somewhere in some
> documentation that I've obviously not properly taken on board.

coef(summary(lm(nu1 ~ nu2)))[,2]

  Also, try the following which is often useful:

str(summary(lm(nu1 ~ nu2)))

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-- 
Chuck Cleland, Ph.D.
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