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From |
Nick Cox <njcoxstata@gmail.com> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: rescaling a variable by the maximum value question |

Date |
Sat, 13 Oct 2012 12:45:38 +0100 |

"What Jay is missing" is better corrected to "What Jay understands" ... On Sat, Oct 13, 2012 at 10:23 AM, Nick Cox <njcoxstata@gmail.com> wrote: > Justina is correct. You can create a new variable, but there is no > need to do that. > > su age, meanonly > gen age2 = age / r(max) > > -su, meanonly- is more efficient when you just want a maximum. (The > name -meanonly- is not indicative here.) That's unimportant in one-off > cases, but a detail to note if doing this repeatedly. > > SJ-7-3 st0135 . . . . . . . . . . . Stata tip 50: Efficient use of summarize > . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . N. J. Cox > Q3/07 SJ 7(3):438--439 (no commands) > tip on using the meanonly option of summarize to more > quickly determine the mean and other statistics of a > large dataset > > What Jay is missing is that -max()- will in his context not return a > scalar that is the maximum of a variable. In fact Stata functions > typically do not that, return a scalar that summarizes a variable. > -max()- wants two or more arguments and will return the result of > comparing them, as it were rowwise. If -max(x, y)- were calculated > from two variables -x- and -y-, then there is scope for a new variable > to be produced. > > Nick > > On Sat, Oct 13, 2012 at 9:02 AM, Justina Fischer <JAVFischer@gmx.de> wrote: >> you can generate a variable that takes on the maximum value >> >> e.g. >> >> su age >> gen var = `r(max)' >> >> gen newvar = oldvar/var >> >> >> see also return list after the sum command > > "JVerkuilen (Gmail)" <jvverkuilen@gmail.com> > >>> I'm sure I'm simply overlooking something easy but I want to make a >>> new variable that is rescaled by dividing by the maximum value of the >>> old one. Old variable: 1, 2, 3, 4. New variable should be 0.25, 0.5, >>> 0.75, 1. >>> >>> The syntax >>> >>> gen newvar = oldvar/max(oldvar) >>> >>> does not work and I understand why it doesn't, because max doesn't >>> work that way. Is there a straightforward way to do this? (Yes I could >>> simply >>> >>> summarize oldvar >>> >>> and pick out the max by hand and rescale. I'd like to avoid that, if >>> possible. ;) * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/faqs/resources/statalist-faq/ * http://www.ats.ucla.edu/stat/stata/

**Follow-Ups**:**Re: st: rescaling a variable by the maximum value question***From:*"JVerkuilen (Gmail)" <jvverkuilen@gmail.com>

**References**:**st: rescaling a variable by the maximum value question***From:*"JVerkuilen (Gmail)" <jvverkuilen@gmail.com>

**Re: st: rescaling a variable by the maximum value question***From:*"Justina Fischer" <JAVFischer@gmx.de>

**Re: st: rescaling a variable by the maximum value question***From:*Nick Cox <njcoxstata@gmail.com>

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