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From |
"Austin Nichols" <austinnichols@gmail.com> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: Re: Memory |

Date |
Thu, 13 Nov 2008 10:09:27 -0500 |

Victor M. Zammit: I also don't understand the point of this exercise--but you should read -help simul- and try e.g. prog makez, rclass syntax [, obs(integer 31)] clear set obs `obs' gen a = invnorm(uniform()) ttest a=0 return scalar t=r(t) end simul, reps(100000) seed(123): makez On Thu, Nov 13, 2008 at 9:56 AM, Nick Cox <n.j.cox@durham.ac.uk> wrote: > I still don't understand what you are trying to do. But I can comment on > your code. > > You are looping round 40,000 times and writing a single result to 40,000 > data files. Then you are looping round to put all those 40,000 data > files in one. > > I'd do that directly this way using just one extra file: > > clear > set obs 31 > gen a = . > tempname out > postfile `out' t using myresults.dta > qui forval i = 1/40000 { > replace a = invnorm(uniform()) > ttest a = 0 > post `out' (r(t)) > } > postclose `out' > > I still doubt 40,000 is anywhere big enough to get an answer. > > Nick > n.j.cox@durham.ac.uk > > Victor M. Zammit > > * 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 . > > > * > * 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/

**Follow-Ups**:**Re: st: Re: Memory***From:*"Victor M. Zammit" <vmz@vol.net.mt>

**References**:**Re: st: Re: Memory***From:*"Victor M. Zammit" <vmz@vol.net.mt>

**RE: st: Re: Memory***From:*"Kieran McCaul" <kamccaul@meddent.uwa.edu.au>

**Re: st: Re: Memory***From:*"Victor M. Zammit" <vmz@vol.net.mt>

**RE: st: Re: Memory***From:*"Nick Cox" <n.j.cox@durham.ac.uk>

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