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From |
"Martin Weiss" <martin.weiss1@gmx.de> |

To |
<statalist@hsphsun2.harvard.edu> |

Subject |
AW: st: random draw of single variable, not whole data |

Date |
Thu, 26 Feb 2009 21:01:55 +0100 |

<> "...0 with probability about 1 in 4 billion" Out of curiosity, how do you calculate that for a continuous random variable? HTH Martin -----Ursprüngliche Nachricht----- Von: owner-statalist@hsphsun2.harvard.edu [mailto:owner-statalist@hsphsun2.harvard.edu] Im Auftrag von Austin Nichols Gesendet: Donnerstag, 26. Februar 2009 20:59 An: statalist@hsphsun2.harvard.edu Betreff: Re: st: random draw of single variable, not whole data Jeph suggests the ceil() solution in a follow-up with the caveat "as long as uniform() never returns precisely 0, which I've never seen" --uniform() is 0 with probability about 1 in 4 billion, so to be safe you could gen y = x[ceil(_N*(1-uniform()))] On Thu, Feb 26, 2009 at 2:33 PM, Austin Nichols <austinnichols@gmail.com> wrote: > With replacement: > gen y = x[round(_N*uniform(),1)+1] > > should be > gen y = x[round(_N*uniform()+.5)] > or > gen y = x[ceil(_N*uniform())] > > I think.... (otherwise you can get _N+1 in the square brackets, for a > missing y, and the prob of getting y[1] is too low) > > On Thu, Feb 26, 2009 at 2:19 PM, Jeph Herrin <junk@spandrel.net> wrote: >> >> It's not clear if you want sampling with or without replacement. >> >> With replacement: >> >> gen y = x[round(_N*uniform(),1)+1] >> >> without replacement: >> >> egen index=rank(uniform()) >> gen y = x[index] >> >> hth, >> Jeph > * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/ * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/

**References**:**st: random draw of single variable, not whole data***From:*Florian Wakolbinger <wakolbinger@drei-e.at>

**Re: st: random draw of single variable, not whole data***From:*Jeph Herrin <junk@spandrel.net>

**Re: st: random draw of single variable, not whole data***From:*Austin Nichols <austinnichols@gmail.com>

**Re: st: random draw of single variable, not whole data***From:*Austin Nichols <austinnichols@gmail.com>

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