# [R] Question: reproducibility of random sampling with replacement

Jeff Newmiller jdnewmil at dcn.davis.CA.us
Thu Jan 2 00:01:32 CET 2014

```If you want to reproduce the same sequence twice, then you need to set the seed at the beginning of each calculation. You are only doing it for the second calculation below.
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Sent from my phone. Please excuse my brevity.

Chee Chen <chee.chen at yahoo.com> wrote:
>Dear All,
>
>I would like to ask for your help on "reproducibility of random
>sampling with replacement". For example, one re-samples the rows with
>replacement of a residual matrix and uses the new residual matrix thus
>obtained to produce a statistic ; repeat this for a certain number of
>times.
>
>My questions:  will the above produce ever be reproducible by setting a
>seed? Namely,  Given the same residual matrix, Ted applies the above
>process and so does Jack, will they get the same results by setting a
>seed?
>
>My attempt: setting seed does not freeze the command "sample" from
>getting different samples, as from the codes:
>====
>x= 1:20
>S = matrix(0,5,20)
>for (i in 1:5) {
>  S[i,] = sample(x, replace=FALSE)
>}
>
>set.seed(123)
>
>T = matrix(0,5,20)
>for (i in 1:5) {
>  T[i,] = sample(x, replace=FALSE)
>}
>sum(S==T)
>===
>
>I would appreciate any comments and/or suggestions on this.
>Regards,
>Chee
>
>	[[alternative HTML version deleted]]
>
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