Moxley, Jerad
2015-Jan-25 02:01 UTC
[R] extracting significance test for individual lm() parameters after using by
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?
[[alternative HTML version deleted]]
Jeff Newmiller
2015-Jan-25 03:04 UTC
[R] extracting significance test for individual lm() parameters after using by
R-square is often a poor indicator of whether a model is appropriate or not.
While it is possible that there exists a package that implements your algorithm
(which you might find using the sos package), I would recommend that you get
some advice from an expert on how to approach this subject, and this list is not
a good place for studying statistics theory (read the Posting Guide). You might
try stats.stackexchange. com.
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On January 24, 2015 6:01:59 PM PST, "Moxley, Jerad" <moxley at
psy.fsu.edu> 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?
>
> [[alternative HTML version deleted]]
>
>______________________________________________
>R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
>https://stat.ethz.ch/mailman/listinfo/r-help
>PLEASE do read the posting guide
>http://www.R-project.org/posting-guide.html
>and provide commented, minimal, self-contained, reproducible code.
Moxley, Jerad
2015-Jan-25 07:02 UTC
[R] extracting significance test for individual lm() parameters after using by
Sorry I was not clearer, but I was asking an R programming question not a theory question. I will try to clarify. If I did this analysis with a dataset involving just one subject the summary command on the lm object would give me a significance test on each parameter fit. The question in this cSe, is the cubic parameter significant? When I try to do this for each subject separately in a larger dataset using the by command, I get the parameter estimate but can't find a significance test. I apologize again for my poor explanation originally,> On Jan 24, 2015, at 10:04 PM, Jeff Newmiller <jdnewmil at dcn.davis.CA.us> wrote: > > R-square is often a poor indicator of whether a model is appropriate or not. While it is possible that there exists a package that implements your algorithm (which you might find using the sos package), I would recommend that you get some advice from an expert on how to approach this subject, and this list is not a good place for studying statistics theory (read the Posting Guide). You might try stats.stackexchange. com. > --------------------------------------------------------------------------- > Jeff Newmiller The ..... ..... Go Live... > DCN:<jdnewmil at dcn.davis.ca.us> Basics: ##.#. ##.#. Live Go... > Live: OO#.. Dead: OO#.. Playing > Research Engineer (Solar/Batteries O.O#. #.O#. with > /Software/Embedded Controllers) .OO#. .OO#. rocks...1 > --------------------------------------------------------------------------- > Sent from my phone. Please excuse my brevity. >> . >
Michael Dewey
2015-Jan-25 12:35 UTC
[R] extracting significance test for individual lm() parameters after using by
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? > > [[alternative HTML version deleted]] > > ______________________________________________ > R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. > > ----- > No virus found in this message. > Checked by AVG - www.avg.com > Version: 2015.0.5645 / Virus Database: 4273/8997 - Release Date: 01/25/15 >-- Michael http://www.dewey.myzen.co.uk