Re:Re: st: use random values in a calculation

[Zhi Su <su.zh@husky.neu.edu>]

Hi ,Eric,

  The ratio to multiply one of the variables could be 0 too. Probably
I do not ask the question right. The variables v1, v2, v3, v4 are
known. The ratios multiply them are chosen from (0,0.05,0.1,0.15,0.2).
Then each variable multiplied by a ratio are sum up. Totally, there
are 5*5*5*5=625 combination for these four variables multipled by a
ratio. Then I generate 625 variables for 625 types of sum.

  Thank you!

Date: Sat, 2 Jul 2011 04:48:49 +0000
From: Eric Booth <ebooth@ppri.tamu.edu>
Subject: Re: st: use random values in a calculation

<>

Here's one approach:

************************
clear
set obs 625
g n = _n
tostring n, replace
g str4 var = "s" + n

**create fake v1-v4 variables for example:
forv nn = 1/4 {
    g v`nn' = runiform()*10
    }

**create random opt1-opt4 to multiply by v1-v4:
forv n = 1/4 {
    g opt`n' = int(runiform()*5)
    replace opt`n' = .05 if opt`n'==1
    replace opt`n' = .1 if opt`n'==2
    replace opt`n' = .15 if opt`n'==3
    replace opt`n' = .2 if opt`n'==4
    }

**create sum of all v*opt vars:
g s = (v1*opt1)+(v2*opt2)+(v3*opt3)+(v4*opt4)
order var s
l  in 1/9
**
keep var s

**use -sxpose- to create s1-s625 variables:
        **-sxpose- is from SSC**
        cap which sxpose
        if _rc ssc install sxpose, replace
sxpose , clear firstnames force destring
************************

- - Eric
__
Eric A. Booth
Public Policy Research Institute
Texas A&M University
ebooth@ppri.tamu.edu



On Jul 1, 2011, at 9:46 PM, Zhi Su wrote:

> Dear Statalists,
>
>  I need to generate a set of variables that are som of four variables
> v1 v2 v3 v4 multipled by a ratio r1 r2 r3 r4 which are randomly chosen
> from (0, 0.05,0.1,0.15,0.2). For example,
> s0=v1*0+v2*0+v3*0+v4*0
> s1=v1*0.05+v2*0+v3*0_v4*0
> s2=v1*0.05+v2*0.05+v3*0+v4*0
> .
> .
> .
> s625=v1*0.2+v2*0.2+v3*0.2+v4*0.2
>
> How can I use commands to generate these 625 variables?
>
> Thank you!
>

-- 
Zhi Su
348 Holmes Hall
Northeastern University
360 Huntington Avenue
Boston, MA 02115
Office:1-617-373-2316
email:su.zh@husky.neu.edu
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