Statalist


[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: st: Re: Memory


From   "Victor M. Zammit" <vmz@vol.net.mt>
To   <statalist@hsphsun2.harvard.edu>
Subject   Re: st: Re: Memory
Date   Thu, 13 Nov 2008 09:41:19 +0100

* a} The data that I have is from generating random samples of whatever
size,in this case of size 31,from a normally distributed,infinitely large,
population; ie

local i = 1

while `i'<= 40000 {

drop _all

set obs 31

gen a = invnorm(uniform())

qui ttest a = 0

replace a = r(t) in 1

keep in 1

save a`i',replace

local i = `i'+1

}

* I use 40000 due to memory constraint.Appending the a[i]'s together gives
me a variable of 40000 observations ,ie

use a1,clear

local i = 2

while `i'<= 40000 {

append using a`i'.dta

local i = `i'+1

}

save ais40000,replace

* b) From ais40000.dta I get the density <= 1.31, presumably to get the
density of 90% , <= 1.697 to get the density of 95% etc etc,according to the
official ttable, ie

capture program drop density

program define density

use ais40000,clear

count if a<= `1'

di " density >=" "`1'" " = " r(N)/40000

end

density 1.31

density 1.697

density 2.042

density 2.457

density 2.75



* For smaller degrees of freedom,the discrepancy is much higher.I would like
to know how if it is at all possible to resolve memory constraint .

----- Original Message ----- 

From: "Kieran McCaul" <kamccaul@meddent.uwa.edu.au>
To: <statalist@hsphsun2.harvard.edu>
Sent: Thursday, November 13, 2008 5:44 AM
Subject: RE: st: Re: Memory


> A couple of people have responded to your previous emails and the
> general thrust of these responses would suggest that no one quite
> understands what it is that you are trying to do.  Frankly, I don't
> understand what it is that you are trying to do.
>
> This makes it difficult to give advice.
>
> So, to resolve this, why don't you explain:
>
> a) what data you have, and
> b) what question or hypothesis you are seeking to address from these
> data
>
>
>
> ______________________________________________
> Kieran McCaul MPH PhD
> WA Centre for Health & Ageing (M573)
> University of Western Australia
> Level 6, Ainslie House
> 48 Murray St
> Perth 6000
> Phone: (08) 9224-2140
> Fax: (08) 9224 8009
> email: kamccaul@meddent.uwa.edu.au
> http://myprofile.cos.com/mccaul
> _______________________________________________
> The fact that no one understands you doesn't make you an artist.
>
>
> -----Original Message-----
> From: owner-statalist@hsphsun2.harvard.edu
> [mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of Victor M.
> Zammit
> Sent: Thursday, 13 November 2008 2:52 AM
> To: statalist@hsphsun2.harvard.edu
> Subject: Re: st: Re: Memory
>
> I have tried to take the average of resulting t-tables after appending
> 40,000 ttests each time,but this practice never seem to converge to one
> value ,not even after days of calculations .
> I have also tried to work with the significant level only ,but this did
> not
> get me anywhere,either.
>
>
>
>
> ----- Original Message ----- 
> From: "Maarten buis" <maartenbuis@yahoo.co.uk>
> To: <statalist@hsphsun2.harvard.edu>
> Sent: Wednesday, November 12, 2008 6:33 PM
> Subject: Re: st: Re: Memory
>
>
> > --- "Victor M. Zammit" <vmz@vol.net.mt> wrote:
> > > I need to t-test an infinit number of random samples of size 30
> ,from
> > > an infinite,normally distributed population. Each t-value is saved
> > > and then appended together to form a database for t table.The
> problem
> > > is that I get constrained by memory regardless of the size of the
> > > memory in my Stata. I have Version 9 .Is there a way of  getting
> > > around this constrained.?
> >
> > If you want to create a table using an infinite number of random
> > samples you need an infinite amount of time and an infinite amount of
> > memory, regardless of what program or computer you use. So that will
> > never work.
> >
> > -- Maarten
> >
> >
> > -----------------------------------------
> > Maarten L. Buis
> > Department of Social Research Methodology
> > Vrije Universiteit Amsterdam
> > Boelelaan 1081
> > 1081 HV Amsterdam
> > The Netherlands
> >
> > visiting address:
> > Buitenveldertselaan 3 (Metropolitan), room N515
> >
> > +31 20 5986715
> >
> > http://home.fsw.vu.nl/m.buis/
> > -----------------------------------------
> >
> >
> >
> > *
> > *   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/
>
>
>
> *
> *   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/



© Copyright 1996–2014 StataCorp LP   |   Terms of use   |   Privacy   |   Contact us   |   What's new   |   Site index