HDTenEightyP/NetNews huggingface dataset:
From: gwills@maths.tcd.ie (Graham Wills)
Newsgroups: sci.math.stat
Subject: Re: Seeding random number generators
Date: 16 Apr 92 08:44:37 GMT
Organization: Dept. of Maths, Trinity College, Dublin, Ireland.

In article <2532@creatures.cs.vt.edu> lavinus@csgrad.cs.vt.edu (Joseph Lavinus) writes:
>Is there a statistically acceptable way to seed a random number generator
>in a computer program?  I'm using the following RNG (the multiplicative
>congruential "minimal standard" published in Communications of the ACM
>a while back):
>
>   Z(i) = 7**5 Z(i-1) mod (2**31 - 1)
>   Z(0) = seed
>
>I've been using the program's process id as a seed, but
>  (a) I'm not at all sure that's a good idea, and
>  (b) Suddenly I need several RNGs simultaneously.
>
>So, the question is, is there a statistically "good" way to seed a number
>(say 10, for concreteness' sake) of RNGs, such that they do not act the same
>each time the program is run, and such that each stream is statistically
>independent of the others, without requiring any intervention from the user?

 As regards (a), the process id may be a perfectly reasonable seed, but one
 of the traditional seeds programmers use is some sort of system call which
 returns a time. On the Macintosh I use a call which gives me the number of
 seconds since midnight, Jan 1, 1900. Other systems allows the number of
 milliseconds since last boot. They're a good bet. Essentially, the problem
 is that a good way to seed is with a random number, which is why you wanted
 a random number generator in the first place ...

 For (b), why do you feel the need for a number of RNGs? Since each result
 taken from the stream is independent of the others (for a good RNG), just
 use one *good* RNG and take all your values from it. If you use several
 RNGs all of the same type, you may end up with highly dependent series
 (Imagine the disaster if they got seeded with values close to each other
 on the cycle; you'd get a perfect lag relationship)

>Also, I'm certainly open to arguments about why I should use a RNG other
>than the one described above...

 A reasonable refernce to examine is "Stochastic Simulation"; B.D. Ripley
 It discusses a number of generators and is fairly application-oriented.

-Graham Wills
 Trinity College Dublin, Ireland
Newsgroups: sci.math.stat
From: bp938@cleveland.Freenet.Edu (Jeffrey G. Thomas)
Subject: Specific examples from Sincich, Statistics by Example
Reply-To: bp938@cleveland.Freenet.Edu (Jeffrey G. Thomas)
Organization: Case Western Reserve University, Cleveland, OH (USA)
Date: Wed, 15 Apr 92 00:27:28 GMT



Notice:  Regarding Terry Sincich's Statistics by Example, 
Dellen Pub. Co., San Francisco (1985), there are some very good
examples of environmental and health and safety regulation which
are apparently based on actual experience.  A synopsis of these
examples is as follows:

Environment:  Air pollution, p.49 (2.35), air pollution standards,
p.114 (3.87), acid rain, p.162 (4.58), p.676 (15.42), toxic waste,
p.194 (5.30), chemicals and cancer, p.206 (5.65), dissolved O2,
p.225, (6.16), dioxin, p.270 (7.37), electric utility thermal
discharge, p.273 (7.46), p.338 (8.85), discharge from sewage plants,
p.274 (7.49), ddt concentration, p.300 (8.27), foam insulation
manufacture, p.304 (8.33), air pollution, p.331 (8.77), lead in gas,
p.381 (9.1), trees grown in greenhouses, p.406 (10.27), pesticide
concentrations, p.406 (10.28), ions in air, p.443 (10.82), total
suspended particulates, p. 549 (12.69), and lead in drinking
water, p.672 (15.33).

Health and safety:  FDA inspection of milk, p.151 (4.35), penicillin,
p.163 (4.59), FDA food labeling requirements, p.169 (4.72), salt and 
hypertension, p.217 (6.81), FDA package weights, p.229 (6.31), low 
tar cigarettes, p.265 (7.25), FDA food content requirements, p.293
(8.12), liquid diets, p.323 (8.64), Reyes syndrome & aspirin, p.330
(8.73), chicken feed contents, p.331 (8.76), drug screens, p.383
(9.3), DDT concentration in fish, p.394 (10.6) (also 11.42 & App.D),
and diet results, 447 (10.94).

I am not now currently taking a course in statistics.  I am
interested in working these problems to obtain the answers 
that are given in Sincich.  Sincich doesn't give commentary on 
these problems. I am interested in the comments of those who have
worked with the textbook and understand the process of setting 
up the models in "real life."

Any comments which emphasize problem solving are welcome. 

Jeff Thomas
From: mfarrall@crc.ac.uk (Martin Farrall)
Newsgroups: sci.math.stat
Subject: 2 x 3 contingency table
Keywords: power calculations, contingency tables
Date: 3 Apr 92 14:37:21 GMT
Reply-To: mfarrall@crc.ac.uk (Martin Farrall)
Organization: MRC Human Genome Mapping Project Resource Centre, Harrow, UK


I wish to be able to compute the appropriate sample size for a 2 x 3 contingency table,
given the expected proportions in each cell, a stringent significance level and a power
of 0.85 (or whatever).  I understand that there are power functions for 2 x 2 tables in the
literature but have been unable to locate any work on 2 x 3 (or k x r) tables.


Any pointers or advice would be appreciated (I won't have to do this by simulation will I!)

Many thanks

Martin Farrall
Newsgroups: sci.math.stat
From: bp938@cleveland.Freenet.Edu (Jeffrey G. Thomas)
Subject: EPA public access computer models
Reply-To: bp938@cleveland.Freenet.Edu (Jeffrey G. Thomas)
Organization: Case Western Reserve University, Cleveland, OH (USA)
Date: Thu, 9 Apr 92 04:22:19 GMT


I have a list of EPA public access computer models which is very
long but not quite exclusive because it doesn't mention some 
of the air pollution models which are contained in the Code of Federal
Regulations, in the appendix.

I also have a copy of Statistics by Example, By Terry Sincich, which
describes quite a few (more than twenty) EPA studies.

The simple analysis of the F statistic, chi square and student's t
in Sincich is the gist of my prior experience.  However, I possess
a copy of Enders A. Robinson's Probability Theory and Applications
and I have read it.  I understand that there are different models
because I have read the Robinson book but I do not have a better grasp
of probability theory as applied because of it.

I am thinking of designing a project to evaluate the EPA computer models
but it would require the assistance of academics and professionals
who could help me to apply the theory to these models (which would
fill this gap in my academic background).

Is there anyone on the network who could at least share some thoughts
on getting started?

Jeff Thomas
From: wsimpson@uwpg02.uwinnipeg.ca
Newsgroups: sci.math.stat,sci.math
Subject: RE: Von Mies(e) circular (probability) distribution
Date: 14 Apr 92 15:47:15 GMT
Organization: University of Winnipeg

An excellent treatment of this topic can be found in:
LOCTN: SCIENCE MAIN STACKS QH 323.5 B388
AUTHR: Batschelet, Edward.
TITLE: Circular statistics in biology / Edward Batschelet. --
PUBLR: London ; Toronto : Academic Press, 1981.

Bill Simpson
wsimpson@uwpg02.uwinnipeg.ca
Newsgroups: sci.math.stat
Subject: Re: SLLN and CLT for dble. index RV ?
From: news@massey.ac.nz (USENET News System)
Date: Wed, 15 Apr 92 22:04:44 GMT
Organization: Massey University

In article <1992Apr15.053451.25886@newshost.anu.edu.au>, Andrew.Robinson@anu.edu.au writes:
> 
> In article <1992Apr15.081401.1@cc.newcastle.edu.au> eemn@cc.newcastle.edu.au
> (Brett Ninness) writes:
> [...]
> >X_1,X_2,.........X_k
> >
> >are different to the variances of the X_j in 
> >
> >X_1,X_2,.........X_k,X_{k+1}.
> >
> >To put it another way, the variance of a particular X_k depends on how
> >may terms I have in the sequence, hence the double indexing.  All the terms
> >are zero mean and independent no matter how long the sequence.
> >
> I'm intrigued.  How can you get a sequence of random variables whose values are
> independent, but whose variances depend on the number of values in the
> sequence?
> 
Easily, if k is chosen first, and then the sequence is observed.

However, if you normalise the sequence, and let the normalised sequence be

     Y_1, Y_2, ..., Y_k

can't you apply the CLT to the Y's?

Terry Moore,  Massey University
From: mwande@qal.qal.berkeley.edu (Mike Anderson)
Newsgroups: sci.math.stat
Subject: re: SPSS export files
Date: 17 Apr 92 05:06:24 GMT
Article-I.D.: agate.slmcgINNbti
Organization: University of California, Berkeley
NNTP-Posting-Host: qal.qal.berkeley.edu


>Copy the file to a new test file. Delete the last line, i.e.
>the one with garbage on it.  You should be okay now.

No, the last line of ZZZ's isn't junk, it's supposed to indicate the
end of the file, I think. I tried  your suggestion anyway, and it
didn't work. The job is stopping much earlier in the file; the error
message says premature end of file encountered while reading "print
format: information, so it isn't even getting to the raw numbers.
That is, it gets stuck somewhere in the variable names/lables part
of the file. 
This is why the SAS conversion runs but yields no observations.
Thanks anyway
Mike

-- 
-----------------------------------------------------------------------------
Mike Anderson    Dept. of Demography   UC Berkeley   mwande@QAL.Berkeley.EDU
"It's the little touches that make a future solid enough to be destroyed."
                                                - William S. Burroughs
From: rjoy@vax5.cit.cornell.edu
Newsgroups: sci.math.stat
Subject: RE: 2x3 contingency table
Date: 11 Apr 92 06:04:54 EST
Distribution: sci
Organization: Cornell University

I would recommend Agresti "Categorical Data Analysis" (1990) Wiley, ppg.239-245
for a discussion of the topic.  His result is basically as follows...

The noncentrality parameter for G2 is

         L = 2n sum[ pi_i log (pi_i/pi_i(M))]

where L is the noncentrality parameter, n is the sample size, pi_i is the set
of hypothetical true cell probabilities, and pi_i(M) is the set of cell
probabilities estimated under some model M.  Agresti (p 242) presents a part of
a full table of the power values for variouL and model df.  

For example, suppose you have a 2x3 table with the following "true" cell
probabilities...

                      .15  .20  .15
                      .05  .10  .35

and you wish to test the model of independence.  Then, the cell probabilities
under themodel would be...

                       .10  .15  .25
                       .10  .15  .25

Now, plugging these values in the above equation, we arrive at:

                    L = 2 n (.104575)

where (.104575) is what you get when you plug the "true" and expected
probabilities into the summation.  Now, looking on the table on pg 242, we can
see that for df=2 (the model of independence for a 2x3 table), and a desired
power value of .883 leads us to a value of L=12.0.  Now, plugging this into our
result, we get

                  12 = 2 n (.104575) = .2091515 n
 
so that          
                       n = 12.0 / .20915 = 57.37

and we now know that we need a sample size of at least 58!


I would recommend Agresti's book for any issue in categorical data analysis
(Gee, that might make a GREAT name for the book!!).

Enjoy!!


Raymond V Liedka
Department of Sociology
Cornell University
Ithaca  NY  14850

e-mail:  rjoy@cornellc
From: tobias@maths.lth.se (Tobias Ryden)
Newsgroups: sci.math.stat
Subject: Ergodic theory for general Markov chains
Date: 9 Apr 92 14:18:13 GMT
Organization: Dept. Statistics & Math, Lund Institute of Technology, Sweden

For a stationary ergodic process X_n it is well known that

       N
  1   ---
  -   \
  N   /    f(X_n) -> E(f(X_1))
      ---
      n=1

with probability 1 and in L_1 provided E|f(X_1)| is finite. Now, let
Y_n be a Markov chain on a general state space E for which there
exists a stationary distribution v, but the initial distribution of
Y, i.e. the distribution of Y_1, need not necessarily equal v.
Under which conditions does

       N
  1   ---
  -   \
  N   /    f(Y_n) -> v(f)
      ---
      n=1

hold, where f is in L_1(v) and the convergence is w.p.1, in L_1 or in
probability?

All references are appreciated!

-- 
+- Tobias Ryden                          Internet: tobias@maths.lth.se
   Dept. of Mathematical Statistics      Tel:   int+46 -(0)46 104276  
   Lund Institute of Technology          Fax:   int+46 -(0)46 104623   
-- P.O. Box 118, S-221 00 Lund, Sweden   
Newsgroups: sci.math.stat
From: Andrew.Robinson@anu.edu.au
Subject: Re: IQRs and hypothesis testing
Reply-To: Andrew.Robinson@anu.edu.au
Organization: Australian National University
Date: Wed, 15 Apr 92 23:31:35 GMT

In article <OLIVER.92Apr15054328@ballard1.mit.edu> oliver@athena.mit.edu (James
D. Oliver III) writes:
>I was using a packaged statistical program to do some simple means testing,
>and notice that in several cases the program didn't do a straightforward
>t-test, but instead "computed the standard error of the difference of means
>assuming IQR(pop.1)/IQR(pop.2)= X".
>
>I found out what IQR is (interquartine(sp?) range) and have a general
                          ^^^^^^^^^^^^^  [interquartile]?
>understanding of what it is, but can find no references on the specifics of
>this particular adjustment and/or the justification for using it.
>
Sounds to me like the package is trying to determine the relative spreads of
the populations because the t-test fails when testing on populations with
differing variances.  The ANOVA does as well, but I don't know of a comparable
procedure.  In fact, that's the first time I've heard of a package which tries
to do this.  Nice.

But I have _no_ idea where to go from here.

>Can anyone point me to some basic, low-level references on this?  Also, if
>there is a similar procedure in conjunction with one-way analysis of
>variance?
>--
>____________________________
>	Jim Oliver  
>	oliver@athena.mit.edu /	joliver@hstbme.mit.edu
>	oliver%mitwccf.BITNET@MITVMA.MIT.EDU
>

regardless,
&rue

Andrew.Robinson@anu.edu.au   <= forestry statistician 
(if it moves, count it; if it doesn't move then CHOP IT DOWN and count it.)
My employers don't care what I say, in fact I don't even think they know I
exist.
From: omlinc@cs.rpi.edu (Christian Omlin)
Newsgroups: sci.math.stat
Subject: Markov Processes and Bayesian Decision Problems
Date: 10 Apr 92 19:09:07 GMT
Article-I.D.: rpi.5w5tgdd
Distribution: usa
Organization: Rensselaer Polytechnic Institute Computer Science, Troy NY

Hi !

I am looking for references on Bayesian decision problems and
Markov processes. In particular, references which give a summary
of results/applications without detailed mathematical derivations
would be helpful. 

If you know of a reference, I would apprciate if you could send
it to the address below as I am not a regular reader of this
newsgroup.

Thanks.

Christian

----------------------------------------------------------------------------
Christian W. Omlin		   Troy, N.Y. 12180 USA			
Computer Science Department        Phone: (518) 276-2930 Fax: (518) 276-4033   
Amos Eaton 119			   E-mail: omlinc@turing.cs.rpi.edu                    
Rensselaer Polytechnic Institute           omlinc@research.nj.nec.com
----------------------------------------------------------------------------
Newsgroups: sci.math
From: bs@gauss.mitre.org (Robert D. Silverman)
Subject: Re: factoid about new prime
Organization: Research Computer Facility, MITRE Corporation, Bedford, MA
Date: Thu, 9 Apr 1992 14:39:44 GMT

In article <SMITH.92Apr8094704@gramian.harvard.edu> smith@gramian.harvard.edu (Steven Smith) writes:
:In article <57048@cup.portal.com> ts@cup.portal.com (Tim W Smith) writes:
:
:> > > This is a (slight) exaggeration. 756839/216091 = 3.5024 times as big.
:> > 
:> > Pardon me, but
:> > 
:> >                756839
:> >               2       - 1                                          162781
:> >               -----------  ~=  2.33397019895780128135136676956 x 10
:> >                216091
:> >               2       - 1
:> >
:> >which is larger than four.  It appears that CNN was conservative in
:> >their report.
:> 
:> No, the *value* of the new prime is 2.3E162781 times the *value* of the old
:> one.  The size is 3.5 times.  It would take 3.5 times as much space to
:> write it.
 
This is correct.

:
:This remains a (silly) semantical argument.  If someone on the street
:offered you $10 for $99 because they are the same size in digits,
:would you accept?
 
It is not silly and it is not a matter of semantics. When one discusses
the run time of algorithms that use large numbers the run time depends
on the SIZE of the inputs. The SIZE is measured by how many bits it has.
The time to multiply two numbers M and N is proportional to log M * log N.
log M and log N are their number of bits. That is to say, their SIZE.

And your argument about $10 vs $99 is itself silly because for large
numbers the difference between log(N) and log(10N) is insignificant.

--
Bob Silverman
These are my opinions and not MITRE's.
Mitre Corporation, Bedford, MA 01730
"You can lead a horse's ass to knowledge, but you can't make him think"
Newsgroups: sci.math
From: edgar@function.mps.ohio-state.edu (Gerald Edgar)
Subject: Re: Zero, "Arabic" numerals, etc.
Organization: The Ohio State University, Dept. of Math.
Date: Wed, 8 Apr 1992 12:42:08 GMT


Back in the olden days, when I was in school in Colorado, we learned
to call them the "Hindu-Arabic numerals".

It is interesting to note that zero was invented in India and in Central
America at approximately the same time.
--
  Gerald A. Edgar                Internet:  edgar@mps.ohio-state.edu
  Department of Mathematics      Bitnet:    EDGAR@OHSTPY
  The Ohio State University      telephone: 614-292-0395 (Office)
  Columbus, OH 43210             -292-4975 (Math. Dept.) -292-1479 (Dept. Fax)
Newsgroups: sci.math
From: hartley@maths.uwa.oz.au (Mike Hartley)
Subject: Re: fun with primes
Keywords: prime numbers
Organization: University of Western Australia
Date: Mon, 6 Apr 1992 08:58:01 GMT

gindrup@math.okstate.edu (Eric `'d'kidd' G..) writes:

>As the earlier proofs have shown,
>(1)  p is assumed to be the largest prime,

But what if there IS no largest prime, because we've just thrown away
the relation '<' ? Can we still do the proof? NB you aren't allowed to
use p! anymore, because p! is the product of all "positive" integers
"less than" or equal to p. Are there an infinite number of primes
in the ring Z[i] = {a+bi:a,b are integers} ? Under what circumstances
does the proof break down? Or are there an infinite number of primes
even in finite integral domains? Is there an infinite integral domain
with a finite (but nonzero) set of primes? Why or why not?

--
+-----------------------------------------------------------------------+
  It has been said that the vast majority of educated people believe in
    evolution because they have been assured that the vast majority of
                 educated people believe in evolution...
Newsgroups: sci.math
From: sunder@jacob.UVic.CA (Sunder  Sreenivasachar)
Subject: Request for info on a good book on optimization
Originator: sunder@jacob
Organization: University of Victoria, Victoria, BC, Canada
Distribution: na
Date: Fri, 10 Apr 92 04:33:12 GMT

I am looking for a good book on optimization which describes 
algorithms in a lucid way. It should include topics like
integer programming, linear programming, line-search methods, 
conjugate-gradient methods, constrained and unconstrained optimization.

I would appreciate your responses by e-mail.

Thanking you in advance.

sunder@sirius.uvic.ca
Organization: Penn State University
Date: Sunday, 12 Apr 1992 00:31:14 EDT
From: S. Wukovitz <SXW103@psuvm.psu.edu>
Newsgroups: sci.math
Subject: Metric on groupings?

Any help would be appreciated:

A friend of mine asked the following question:

Suppose you decide to divide n objects into discrete sets in various
ways.  Is there some metric on the set of all possible groupings?
i.e. if you had

     grouping 1:  ACD E BF
     grouping 2:  E ADC BF

the distance between them would be 0, but

     grouping 1:  ABCD E F      and
     grouping 2:  ABC D EF

would be nonzero, and the metric this distance would otherwise
behave like a metric is supposed to.

PLEASE DO NOT SEND MAIL TO ME!!  If you need to mail my friend,
he is SML108@PSUVM (bitnet) or SML108@psuvm.psu.edu.  Please
try to post any thoughts you might have...

Thank-you!

-Stephanie
Newsgroups: sci.math
From: nave@cs.swarthmore.edu (Lee Nave)
Subject: need good intro simplical homology
Organization: Swarthmore College, Swarthmore, PA, USA
Distribution: usa
Date: Mon, 13 Apr 1992 22:47:31 GMT


     I'm taking an undergraduate seminar in topology.  For the first half of
the seminar we used Munkres' Topology.  I found it an excellent textbook.
Now we're working on simplical homology and reading from Armstrong's Basic
Topology.

     Can anyone recommend a better introductory undergraduate-level text, if
such a thing exists?  Any advice would be appreciated.

Thanks,

Lee Nave
nave@cs.swarthmore.edu
Newsgroups: sci.math
From: martin@lyra.cis.umassd.edu (Gary Martin)
Subject: Re: factoid about new prime
Organization: University of Massachusetts Dartmouth
	<1992Apr7.150455.22306@news.eng.convex.com>
	<1992Apr9.111809.19221@linus.mitre.org>
Date: Fri, 10 Apr 1992 14:25:53 GMT

In article <1992Apr9.111809.19221@linus.mitre.org> bs@faron.mitre.org (Robert D. Silverman) writes:


   :>In article <3987@crl.LABS.TEK.COM> scott@ferrari.LABS.TEK.COM (Scott Huddleston) writes:
   :>:It was mentioned on CNN that the new prime number discovered
   :>:recently is four times bigger then the previous record.
   :> 

   4 times as big as P does NOT equal 4P. Size is measured by number of
   bits. 4 times as big means 4 times as many bits. CNN got it RIGHT.
   Most people here are getting it wrong.
   --
What are the chances that CNN understood why what they said was right?
(Particularly considering that there are people here who don't.)
If one takes a skeptical view of the popular media's understanding
of math, it does make a good joke.

--
Gary A. Martin, Assistant Professor of Mathematics, UMass Dartmouth
Martin@cis.umassd.edu
From: e343mh@tamuts.tamu.edu (Michael Hand)
Newsgroups: sci.math
Subject: Archives?
Date: 13 Apr 92 22:11:16 GMT
Organization: Texas A&M University, College Station

Can someone please email with info on where sci.math is archived 
and how to access the archives?
Thanks much.
Michael
From: dabbott@augean.eleceng.adelaide.edu.AU (Derek Abbott)
Newsgroups: sci.math
Subject: Fermat's Last Theorum
Date: 8 Apr 92 08:11:34 GMT
Organization: Electrical and Electronic Eng., University of Adelaide

One of the tantalizing things about FLT is the fabled note that Fermat
left before he died saying that he found an elegant proof.

There are two main possibilities:

(a) He really found the proof, and the historical record is lost

(b) He had a mental abberation, and this mistaken proof is lost too


Out of curiostity, I was wondering whether people in the maths community
have given up hope of believing in (a) and now subscribe to (b), or
whether belief in (a) is still strong?
From: dnf@suned1.nswses.navy.mil (David N Fukes)
Newsgroups: sci.math
Subject: Math term paper subject requested
Date: 10 Apr 92 22:18:49 GMT
Organization: US Navy (NSWSES)


I am a part-time undergraduate math student and am faced with having to write a  
a short ten page term paper on one of two of the following subjects:
a modern mathematical development (i.e., something within the last 10-15 years)
or a modern mathematician (preferably one that is still living).  I would
appreciate any suggestions regarding a specific topic on any of these general
areas.

Thanks for the help in adavance.
-- 
David N. Fukes               | dnf@suned1.nswses.navy.mil
NSWSES Code 4V12             |
Port Hueneme, CA 93043-5007  |
(805)982-9348