st: RE: using loop to generate distributions with different means and standard deviations

["Sarah Edgington" <sedging@ucla.edu>]

Lance,
Is your actual data really different from the simulated data you've shown?
If not I don't understand why the solution I suggested before doesn't solve
your problem. If your variables are actually numbered like you've shown,
it's still just a -forvalues- loop to get the drawnorm part working.

forv i=1/3 {
	drawnorm product`i', m(max_product`i') sd(sd_product`i')
}

Unless you give more specific information about the actual problem you're
trying to solve and why the suggested solution doesn't work, I don't think
you're going to get much help.

-Sarah



-----Original Message-----
From: owner-statalist@hsphsun2.harvard.edu
[mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of Lance Wiggains
Sent: Friday, May 20, 2011 11:29 AM
To: statalist@hsphsun2.harvard.edu
Subject: st: using loop to generate distributions with different means and
standard deviations

Sorry for the vagueness. Right now I'm just using simulated data for 3
different products. Here is my code:
My data looks like this
Week      Product 1        Product 2      Product 3
1                  50                 45                 50
2                  60                 50                 40
3                  70                 55                 30
4                  80                 50                 20
5                  90                 45                 10
6                  100               50                  0

tsset week
gen n=_n
egen max_n=max(n)

ds week n max_n, not
foreach var in `r(varlist)'{
       tssmooth ma ms_`var'= `var', weights(1 1<2>1)
       }

ds ms*
foreach var in `r(varlist)' {
       gen week3_`var'=`var' if n==max_n
       egen max_week3_`var'=max(week3_`var')
       drop week3*

}
drop ms*

ds week n max_*, not
foreach var in `r(varlist)' {
       gen max_`var'=max_week3_ms_`var'
}
drop max_week*

keep if n+3>=max_n
ds week n max*, not
foreach var in `r(varlist)'{
       egen sd_`var'=sd(`var')
}

rename max_n maximum_n

ds max_* sd* week, not
foreach var in `r(varlist)'{
       drop `var'
}

drawnorm product1, m(max_product1) sd(sd_product1)

Thanks,

Lance
- Hide quoted text -

On Wed, May 18, 2011 at 1:51 PM, Sarah Edgington <sedging@ucla.edu> wrote:
> Lance,
> That's a different problem.  From your original post I assumed you had 
> all the variables already created.
> One strategy for writing loops is to write out the code for the first 
> two examples of something repetitive you want to do.  Then identify 
> the parts of the example that remain the same across the examples.
> If you post the code your trying to repeat we may be able to help you 
> but your current description is too vague for me to do much more than 
> offer vague suggestions of how to think about loops.
> -Sarah
>
> -----Original Message-----
> From: owner-statalist@hsphsun2.harvard.edu
> [mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of Lance 
> Wiggains
> Sent: Wednesday, May 18, 2011 10:36 AM
> To: statalist@hsphsun2.harvard.edu
> Subject: Re: st: RE: using loop to generate distributions with 
> different means and standard deviations
>
> I've tried that but the problem is that I'm pre-calculating the means 
> and sd's for the variable because I'm only using the last 3-4 
> observations for each variable to calculate those values. I'm doing 
> this because I want it to reflect the changes that happen recently. My 
> mean function uses tssmooth, with weights (1 1<2>), to average the 
> last 3 weeks of sales. So if sales were 70,80,90, and 100 I get a 
> value of 92.5 for my mean. It also calculates a SD for the last 3-4 
> observations. Then I want to plug those numbers into the drawnorm function
using a loop. Any idea about how that would work?
>
> Lance
>
> On Wed, May 18, 2011 at 1:16 PM, Sarah Edgington <sedging@ucla.edu> wrote:
>> Lance,
>> Try something like this:
>>
>>        forv i=1/3 {
>>                 drawnorm name`i', m(mean_var`i') sd(sd_var`i')
>>        }
>>
>> You'll run into problems, though, if your data actually includes the 
>> variable names you list since there isn't a sd_var1.
>>
>> -Sarah
>>
>> -----Original Message-----
>> From: owner-statalist@hsphsun2.harvard.edu
>> [mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of Lance 
>> Wiggains
>> Sent: Wednesday, May 18, 2011 10:09 AM
>> To: statalist@hsphsun2.harvard.edu
>> Subject: st: using loop to generate distributions with different 
>> means and standard deviations
>>
>> Statalist members,
>>
>> I'm trying to get Stata to generate a distribution of data from 
>> variables in my data set.
>>
>> My appended data looks like this
>> mean_var1=90
>> standard_deviation_var1=5
>> mean_var2=100
>> sd_var2=10
>> mean var3=110
>> sd_var3=15
>> and so on
>>
>> I'm need a loop that will take my variables and create the 
>> distributions for me.
>> I've been using the drawnorm command
>>     drawnorm name1, m(mean_var1) sd(sd_var1) but I can't get it to 
>> recognize more than 1 variable at a time
>>
>> I want it to perform the distribution command for each pair of my
> variables.
>> I.e. (m_var1, sd_var1), (m_var2, sd_var2) , (m_var3, sd_var3)
>>
>> Thanks for your consideration,
>>
>> Lance
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