[R] extracting significance test for individual lm() parameters after using by

[Michael Dewey]

Dear Jerad

I may have completely misunderstood your question but you do know that 
you can write your own function and use it in sapply where you have 
summary? You could incorporate calls to summary or to coef or somet 
other extractor or you could use the $ tool.

On 25/01/2015 02:01, Moxley, Jerad wrote:
> I’m trying to test what growth functions best fit individual subjects. I’m wanting compare linear, quadratic, cubic etc.  Here is the example from the cubic curve.
>
> b3a<-by(c,id,function(x) lm(w~agec+ageq+agecub,data=x))
>
> I can get quiet a bit of information out of sapply(b3a,summary) but it reports something like this for each person
>                37
> call          Expression
> terms         Expression
> residuals     Numeric,62
> coefficients  Numeric,16
> aliased           Logical,4  4
> sigma         67.05895
> df            Integer,3
> r.squared     0.9822921
> adj.r.squared 0.9813762
> fstatistic    Numeric,3
> cov.unscaled  Numeric,16
>
> I could obviously compute by hand the r squared change and then compute a p value based for what the partial r is for the variable but I’d like to have a simpler solution to it. Can I get the information or is there an package that I should download that will do what I’m trying to do much simpler?
>
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>
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-- 
Michael
http://www.dewey.myzen.co.uk