opensta-users

[OpenSTA-users] Why isn't my Random variable very random?

[Stephen K. <Ste...@on...>]

I can't quite get the hang of random variables and I'm sure I'm missing
something, but I've looked at the help, sourceforge and tried some tests,
but can't work out what I'm doing wrong.

To highlight the problem I created a tiny script.

I have this line in my definition section of script:

      Integer           userthinktime     (5000 - 20000), RANDOM

Then in the code section of my script I have these lines:

      generate userthinktime
      log userthinktime

If I run this script in the modeler it logs a random value each time and
that's good.  However, when I run this as a test for 10 seconds with 10
users running the same script I get this sort of thing in the logs (i.e. it
increments by a few milliseconds each time):
LOG: 13373,
LOG: 13376,
LOG: 13379,
LOG: 13382,
LOG: 13386,
LOG: 13389,
LOG: 13395,
LOG: 13399,
LOG: 13405,
LOG: 13409,
LOG: 13412,
LOG: 13425,
LOG: 13428,
LOG: 13431,


What I want is a genuinely random variable picked up by each virtual user
running the script, but I can't work out how to do it.  I'll keep trying
but if anyone knows how to do this I'd appreciate a nudge in the right
direction.

Thanks, Steve



For the latest data on the economy and society consult National Statistics at http://www.statistics.gov.uk

*********************************************************************************


Please Note:  Incoming and outgoing email messages are routinely monitored for compliance with our policy on the use of electronic communications
*********************************************************************************


Legal Disclaimer  :  Any views expressed by the sender of this message are not necessarily those of the Office for National Statistics
*********************************************************************************


The original of this email was scanned for viruses by the Government Secure Intranet Anti-Virus service supplied by Cable&Wireless in partnership with MessageLabs. (CCTM Certificate Number 2006/04/0007.) On leaving the GSi this email was certified virus free.
Communications via the GSi may be automatically logged, monitored and/or recorded for legal purposes.

Re: [OpenSTA-users] Why isn't my Random variable very random?

[Bernie V. <Ber...@iP...>]

Hi Stephen,

I think I understand what is happening, but I'm going suggest a workaround 
instead of guessing or putting in the time to nail this down.

Workaround: If you don't like the random numbers generated by OpenSTA ( and 
depending on the version you have, there are some known bugs I think), you 
could always generate a list outside OpenSTA and import them...

 integer userthinktime (19624, 15201, 11692, 10762, 10927, 8732, 15496, &
       5387, 7544, 19403, 15315, 19253, 12551 ),  script ! This list was 
generated in excel using int(5000+rand()*15000)
                                                                             
            ! This list can be much longer
                                                                             
            ! Note the scope is SCRIPT... think about it.

next userthinktime
log userthinktime

-Bernie

Need rapid response OpenSTA support and bug fixes?
Learn more at http://iperformax.com/services.html




----- Original Message ----- 
From: "Stephen Kay" <Ste...@on...>
To: <ope...@li...>
Sent: Wednesday, August 15, 2007 4:58 AM
Subject: [OpenSTA-users] Why isn't my Random variable very random?


>I can't quite get the hang of random variables and I'm sure I'm missing
> something, but I've looked at the help, sourceforge and tried some tests,
> but can't work out what I'm doing wrong.
>
> To highlight the problem I created a tiny script.
>
> I have this line in my definition section of script:
>
>      Integer           userthinktime     (5000 - 20000), RANDOM
>
> Then in the code section of my script I have these lines:
>
>      generate userthinktime
>      log userthinktime
>
> If I run this script in the modeler it logs a random value each time and
> that's good.  However, when I run this as a test for 10 seconds with 10
> users running the same script I get this sort of thing in the logs (i.e. 
> it
> increments by a few milliseconds each time):
> LOG: 13373,
> LOG: 13376,
> LOG: 13379,
> LOG: 13382,
> LOG: 13386,
> LOG: 13389,
> LOG: 13395,
> LOG: 13399,
> LOG: 13405,
> LOG: 13409,
> LOG: 13412,
> LOG: 13425,
> LOG: 13428,
> LOG: 13431,
>
>
> What I want is a genuinely random variable picked up by each virtual user
> running the script, but I can't work out how to do it.  I'll keep trying
> but if anyone knows how to do this I'd appreciate a nudge in the right
> direction.
>
> Thanks, Steve
>
>
>
> For the latest data on the economy and society consult National Statistics 
> at http://www.statistics.gov.uk
>
> *********************************************************************************
>
>
> Please Note:  Incoming and outgoing email messages are routinely monitored 
> for compliance with our policy on the use of electronic communications
> *********************************************************************************
>
>
> Legal Disclaimer  :  Any views expressed by the sender of this message are 
> not necessarily those of the Office for National Statistics
> *********************************************************************************
>
>
> The original of this email was scanned for viruses by the Government 
> Secure Intranet Anti-Virus service supplied by Cable&Wireless in 
> partnership with MessageLabs. (CCTM Certificate Number 2006/04/0007.) On 
> leaving the GSi this email was certified virus free.
> Communications via the GSi may be automatically logged, monitored and/or 
> recorded for legal purposes.
>
> -------------------------------------------------------------------------
> This SF.net email is sponsored by: Splunk Inc.
> Still grepping through log files to find problems?  Stop.
> Now Search log events and configuration files using AJAX and a browser.
> Download your FREE copy of Splunk now >>  http://get.splunk.com/
> -- 
> OpenSTA-users mailing list Ope...@li...
> Subscribe/Unsubscribe/Options: 
> http://lists.sf.net/lists/listinfo/opensta-users
> Posting Guidelines: 
> http://portal.opensta.org/faq.php?topic=UserMailingList