Hello, Vector y is an alphabetically sorted version of vector x. Will both samples, X and Y, be "absolutely" random or will they have systematic differences? And: Should I sort or shuffle a vector before sampling? Thank you, *S* x <- as.factor(LETTERS[sequence(10:1)]) y <- sort(x) X <- sample(x, 5) Y <- sample(y, 5) -- Sascha Vieweg, saschaview at gmail.com
Define: "Absolutely random"; "systematic differences" (All pseudorandom numbers are by definition generated by a deterministic algorithm from a possibly random starting seed set). On Wed, Aug 15, 2012 at 9:11 AM, <saschaview at gmail.com> wrote:> Hello, > > Vector y is an alphabetically sorted version of vector x. Will both samples, > X and Y, be "absolutely" random or will they have systematic differences? > And:Should I sort or shuffle a vector before sampling? No. -- Bert> > Thank you, *S* > > x <- as.factor(LETTERS[sequence(10:1)]) > y <- sort(x) > X <- sample(x, 5) > Y <- sample(y, 5) > > > -- > Sascha Vieweg, saschaview at gmail.com > > ______________________________________________ > R-help at r-project.org mailing list > 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.-- Bert Gunter Genentech Nonclinical Biostatistics Internal Contact Info: Phone: 467-7374 Website: http://pharmadevelopment.roche.com/index/pdb/pdb-functional-groups/pdb-biostatistics/pdb-ncb-home.htm
This seems more theoretical than specific to R, so you should discuss this
question in a more theoretical forum such as http://stats.stackexchange.com/.
FWIW I believe the results will be equally random either way. That doesn't
say either way will be "absolutely" random, since I don't think
such a thing is possible.
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Sent from my phone. Please excuse my brevity.
saschaview at gmail.com wrote:
>Hello,
>
>Vector y is an alphabetically sorted version of vector x. Will both
>samples, X and Y, be "absolutely" random or will they have
systematic
>differences? And: Should I sort or shuffle a vector before sampling?
>
>Thank you, *S*
>
>x <- as.factor(LETTERS[sequence(10:1)])
>y <- sort(x)
>X <- sample(x, 5)
>Y <- sample(y, 5)
>
>
>--
>Sascha Vieweg, saschaview at gmail.com
>
>______________________________________________
>R-help at r-project.org mailing list
>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.