On Nov 21, 2009, at 8:03 AM, bbslover wrote:
>
> Hi?all friends,
>
> Please help me understand this sentence below:
> ?From this set, 858 columns not significantly correlated with the
> response variable TBG at the 5% level were removed, leaving a set of
> 390
> columns.? and ? the F-test's value for the one-parameter
> correlation with
> the descriptor is below 1.0? is equal?? I want to perform this
> above
> sentence with R, how can I do? I just try it below. but I do not
> know right
> or wrong?
It appears to me that you do not understand even basic statistics. As
a corollary to that impression I would suggest that giving you advice
about the use of R for scientific investigation could be morally
similar to giving you advice about how to do your own household
wiring. The best advice would be consult with someone who can offer
guidance based on a proper understanding of statistical principles.
(And if this is course homework, you should not have posted here in
the first place.)
>
> about the above sentence, my idea is like this p.value<0.5, and i
> write a
> code to perform it below:
>
>
> xmat4<-xmat3[,apply(xmat3,2,function(.col)!all(var.test(.col,y)
> $p.value<0.05))]
> , is right? does the above sentence refer to p.value or F.value? I
> do not
> know, please help me! And how can I get the F.value?
>
> About this sentence "A further 367 columns with variance below 1.0
> kcal/mol were removed as recommended,16 leaving 23 columns."
> my code below:
> xmat3<-xmat2[,apply(xmat2,2,function(.col)!all(var(.col)<1))], can
> I change
> the var to sd? I have tried it. They have the same result, generally
> speaking? which one will be used to see the variation of the data?
If you knew even basic statistics, you would realize that the sd is
the square root of the variance. As it happens you have chosen the one
threshold or cutpoint ( == 1) where those two values are equal for a
set. It is not generally true that you can chose the same cutpoint for
using variance and standard deviation.
>
> Thank you!
>
> kevin
> --
> View this message in context:
http://old.nabble.com/p.value---OR---F.value--tp26456379p26456379.html
> Sent from the R help mailing list archive at Nabble.com.
>
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> and provide commented, minimal, self-contained, reproducible code.
David Winsemius, MD
Heritage Laboratories
West Hartford, CT