Herman Rubin wrote:
ExpVar = -ln(UnifVar);
It is not a good method in the tails, and is much too slow.
If I recall correctly, transcendental operations on a Pentium require
only a couple hundred clock cycles and can usually be optimized to take
place during other
Next question:
How much does Rasch analysis depend upon the evaluators being ignorant
that the method will be used?
In other words, can
(A) one Rasch-aware judge
(B) a minority of Rasch-aware judges
(C) a majority of Rasch-aware judges (but not the
AP wrote:
Hi all:
I would appreciate your help in solving this question.
calculate the standard deviation of a sample where the mean and
standard deviation from the process are provided?
E.g. Process mean = 150; standard deviation = 20. What is the SD for
a sample of 25? The answer
Linda wrote:
I want to generate a series of random variables, X with exponential
PDF with a given mean,MU value. However, I only want X to be in some
specified lower and upper limit?? Say between 0 - 150 i.e. rejected
anything outside this range Does anyone have any ideas how should I do
Alan Miller wrote (six times):
Linda wrote in message [EMAIL PROTECTED]...
I want to generate a series of random variables, X with exponential
PDF with a given mean,MU value. However, I only want X to be in some
specified lower and upper limit?? Say between 0 - 150 i.e. rejected
anything
J. Random Loser in Dnepropetrowsk wrote:
The Listsoft Co company offers save your money.
We prepositionals the softwere.
Ah. That really fills me with confidence.
The are :
1. MS WINDOWS 2000 PROFESSIONAL + (SERVICE PACK 2)- 1CD -$15
Melady Preece wrote:
A student wants to know how one can calculate the area under the curve
for skewed distributions. Can someone give me an answer about when a
distribution is too skewed to use the z table?
You can only use the z table directly to find the area under a curve
[EMAIL PROTECTED] wrote:
Hello,
My name Steven Lee. I am a programmer and the best.
I can hack into any Paypal order form and get
membership for free.
Is a Paypal order form something like Opus Dei?
If you no believe me see my
site
Case, Brad wrote:
Hello. I am hoping that my question can be answered by a statistical
expert out there!! (which I am not). I am carrying out a multiple linear
regression with two independents. It seems that a square root
transformation of the dependent variable effectively
Lucas Wells wrote:
So, what I often see, then is:
Orders (note: presented as Aug, Sep, Oct):
Orders Issue: 1, 9000, 9500
Orders With Errors: 2000, 2500, 2250
% Orders With Errors: 20%, 27.78%, 23.68%
Fields With Errors:
Name Field: 750, 1000, 1100
Address Field: 750, 900,
Moataz wrote:
Dear All,
Can anyone tell me where to find source code or even the
algorithm for simulating The normal distribution and the Exponential
distribution ?
Exponential distribution is easy: the negative logs of uniform random
numbers are exponentially
[NOTE: this is CC'd to EDSTSAT-L]
Stan Brown wrote:
... Now we come to the part I'm having conceptual trouble with: Have
you proven that one gas gives better mileage than the other? If so,
which one is better?
Now obviously if the two are different then one is better, and if
one is
Brad Guth wrote:
My URL has much to do with the discovery of GUTH Venus
http://geocities.com/bradguth
One of my questions has to deal with a manned mission, which may need
to utilize the orbit station L2, as an orbit situated so as to sustain
life onboard the spacecraft for several
Art Kendall wrote:
. Mathematical
statisticians need more course work than general statisticians. Many
agencies pay 15% more to a math statistician than a general
statistician.
So what you're saying is that it isn't a
Jerry Dallal wrote:
Robert J. MacG. Dawson wrote:
Art Kendall wrote:
. Mathematical
statisticians need more course work than general statisticians. Many
agencies pay 15% more to a math statistician than a general
Nathaniel wrote:
Hi,
Sorry for question, but how is the english word for @
Pleas forgive me.
You're forgiven...grin
The New Hacker's Dictionary gives:
common: at sign; at; strudel
rare (and often facetious): vortex, whorl, whirlpool , cyclone, snail,
ape,
Jim Snow wrote:
1. George Marsaglia and Wal Wan Tsang published a paper dealing with
your problem which gives an efficient procedure for all values of
parameters. It is
The Monty Python Method for Generating Gamma Variables
in the Journal of Statistical Software
Stan Brown wrote:
I see why the quality controller would want to
do a two-tailed test: the product should not be outside
manufacturing parameters in either direction. (Presumably the QC
person would be testing the pills themselves, not patients taking
the pills.)
Ludovic Duponchel wrote:
If x values have a normal distribution, is there a normal distribution
for x^2 ?
No. If the mean is 0, x^2 hasa chi-squared distribution with 1 DOF.
As the ratio mean/SD - infinity, the distribution of x^2 is
asymptotically normal.
-Robert Dawson
Stan Brown wrote:
On a quiz, I set the following problem to my statistics class:
The manufacturer of a patent medicine claims that it is 90%
effective(*) in relieving an allergy for a period of 8 hours. In a
sample of 200 people who had the allergy, the medicine provided
relief for 170
Gaj Vidmar wrote:
sample size | distribution(s) | population var | appropriate test
--
large (say, N30) | normal | known | z (obvious)
No, here large is irrelevant. N=1
Speaking of normal distributions and cancer clusters, does anybody (a)
agree with me that the human race in general has a better feel for the
normal distribution than the binomial distribution, and the Poisson is
still worse - and (b) know of any experimental evidence for this?
That is, my
The NY Times wrote:
It is no longer possible to serve competently on some juries
without more data skills than most college graduates have.
That's all right, there will always be one lawyer or the other who
doesn't *want* anybody to serve competently, and the competent juror
On 20 Nov 2001, J. Peter Leeds wrote:
The problem actually breaks down to a rather simple analogy:
Imagine that a man has been sentenced by court to run a gauntlet
composed of four club-wielding executioners.
(ill-defined, and thus insoluble, problem omitted)
and Donald
Jerry Dallal wrote:
But, if the null hypothesis is that the means are the same, why
isn't(aren't) the sample variance(s) calculated about a pooled
estimate of the common mean?
I looked at this some years ago. The answer is straightforward: it
would be logically valid to do so but you
Dennis Roberts wrote:
At 08:51 AM 11/15/01 -0600, jim clark wrote:
The Ho in the case of means is NOT about the variances, so the
analogy breaks down. That is, we are not hypothesizing
Ho: sig1^2 = sig2^2, but rather Ho: mu1 = mu2. So there is no
direct link between Ho and the SE,
No Spam Mapson wrote:
The OED cites the following use of metric as a noun:
1921 Proc. R. Soc. A. XCIX. 104 In the non-Euclidean
geometry of Riemann, the metric is defined by certain quantities ...
A good example of bad usage: *what* metric, *what* quantities?
The reader should not be
Chia C Chong wrote:
I am a beginner in the statistical analysis and hypothesis. I have 2
variables (A and B) from an experiment that was observed for a certain
period time. I need to form a statistical model that will model these two
variables. As an initial step, I plot the histograms of
Nomen Nescio wrote:
Mr. Dawson wrote:
Well, they do say what goes around comes around; I'd love to see what
mark the dishonest DL student gets having had his homework done for him
by somebody who:
(a) believes all primes to be odd;
...
### Let's assume
Glenn Barnett wrote:
(1) normality is rarely important, provided the sample sizes are
largish. The larger the less important.
The a.r.e won't change with larger samples, so I disagree here.
I don't follow. Asymptotic relative efficiency is a limit as sample
sizes go
Desmond Cheung wrote:
Is there any mathematical analysis to find how much the two peaks stand
out from the other data? Is there any formulas to find the
variance/deviation/etc that's similar to the unimodal distribution case?
In answer to the latter question - excatly the ones you
Well, they do say what goes around comes around; I'd love to see what
mark the dishonest DL student gets having had his homework done for him
by somebody who:
(a) believes all primes to be odd;
(b) believes that A=B implies B=A;
(c) has never heard of
Voltolini wrote:
Hi, I am Biologist preparing a class on experiments in ecology including
a short and simple text about how to use and to choose the most commom
statistical tests (chi-square, t tests, ANOVA, correlation and regression).
I am planning to include the idea that testing the
One what? Any statistic that depends on the units used seems rather
arbitrary to me. If I compute the range of weights of a group of people
(in kilograms) I ought to get the same actual *weight* as an American
using pounds or a Brit using stones.
On a lighter note - sorry -
jeff rasmussen wrote:
Dear statistically-enamored,
There was a question in my undergrad class concerning how to define the
range, where a student pointed out that contrary to my edict, the range was
the difference between the maximum minimum. I'd always believed that
the
david007 wrote:
Let A denote the maximum run length, i.e. the
largest number of consecutive heads we get among the n tosses.
Find P(A=2) analytically (not by simulation) for the case n=5.
Try rephrasing. A=2 means that (1) there are two heads in a row and
Nimish Shah wrote:
Dear DL Students,
I have Ph.D. degree in mathematics, physics, electrical engineering,
computer science.
Can you please post details of your 3 PhDs!
Four, surely?
-R. Dawson
=
Dennis Roberts wrote:
it seems to me that the notion of a confidence interval is a general
concept ... having to do with estimating some unknown quantity in which
errors are known to occur or be present in that estimation process
in general, the generic version of a CI is:
Emord Nila Palindrome wrote:
It is certainly bad usage, for the following reason: the phrase,
the metric, implies that there is *one* metric function on
Riemannian geometry, which is false. This reason has nothing
to do with distance measure in general, as commonly understood,
or
Robert J. MacG. Dawson wrote:
Actually, there *is* essentially one canonical metric function on
Riemannian geometry. In either model of absolute geometry there is, up
to a multiplicative constant, only one metric preserved by reflection.
In hyperbolic geometry, moreover
Jerry Dallal wrote:
You can have them count the colors of candies in bags of MMs. The MM
web site has the expected proportions published so they can do a
ChiSquare test against those proportions.
Does anybody really care about the proportions of different colors
in bags of MMs?
@Home wrote:
Is there any downloadable freeware that can generate let's say 2000 random
samples of size n=100 from a population of 100 numbers.
and Randy Poe responded:
Um.
A sample of 100 from a population of 100 is going to
give you the entire population.
Depends whether
Rich Ulrich wrote:
Robert waffles by saying 'most' purposes, so I have to
find it easy to agree. When might you *not* treat a uniform,
N=20 as normal? - perhaps when the R^2 is too high
(above .90)?
Anything involving extreme-value estimation, for a start.
@Home wrote:
Is there any downloadable freeware that can generate let's say 2000 random
samples of size n=100 from a population of 100 numbers.
and Randy Poe responded:
Um.
A sample of 100 from a population of 100 is going to
give you the entire population.
I replied:
Jon Cryer wrote:
Robert:
even when N=20, a uniform distribution can be treated as
normal for most purposes.
I assume you meant to say that for N=20, the sample mean based on a random
sample from a uniform distribution can be assumed to have a normal
distribution
for most purposes.
JHWB wrote:
Hm, hope I didn't make that subject to complex, resulting in zero replies.
But hopefully you can answer this:
I have a N(20,5) distribution and based on that I generated 25 values using
Minitab and the CalcRandom dataNormal function. The result yielded a mean
of 19,083 and
The implausibly named aaaaaaaaa wrote:
I would like to ask how to convert teragram to kilogram.
Thanks for helping~
Try
http://www.tuxedo.org/~esr/jargon/jargon.html#quantifiers
for a good rundown on this. Or multiply by 10^9.
( By the way, aa (may I call
Sorry, I misread the original and sent the teragram - gram conversion.
D'oh!
Teragram - kilogram is of course 10^9.
-Robert Dawson
=
Instructions for joining and leaving this list and remarks about
the
kmswys wrote:
lg*(lg(n)) and lg(lg*n)
lg* is iterated logarithm (base 2), defined as the smallest i such that
ith iteration of logarithm is less or equal one.
lg*(lg(n)) is just lg*(n) - 1, asymptotically ~ lg*(n)
The second expression is thus asymptotically the log of
Jay Larman wrote:
This is a SCAM. Do not fall for it.
On the contrary. If anybody reading this is (which I doubt) the sort
of person who would get involved in laundering money stolen by a
deceased politician in a poor country if the opportunity really arose,
then I urge them:
Sloppy Joe [EMAIL PROTECTED] wrote:
Greetings -
Suppose I have a method such as a fair 6-sided die. I roll the die 10
times and get the following trial history:
3-5-1-3-6-4-6-2-1-5
From what I can recall from probability, I cannot predict the next roll
of the die based on the
Alan McLean wrote:
The composite variable or measure (hopefully) has a reasonably
numeric scale.
I don't think (in light of the Central Limit Theorem) that the problem
is whether the composite's reasonably numeric. It is. The problem,
when the data's given the usual ANOVic treatment,
Paul R. Swank wrote:
...In the bimodal case, some refer to the higher hump as the
major mode and the other as the minor mode.
Followed by Dorian, Ionian, Lydian, Hypodorian, Myxolydian... etc?
g,d,r
-Robert Dawson
Dennis Roberts wrote:
major mode and the other as the minor mode.
this is an interesting point but, one we have to be careful about ... in
the minitab pulse data set ... c6 is heights of 92 college students ...
IIRC, the difference between male and female mean height is almost
I wrote:
Er, no.
Q1 ~ mu - 2/3 sigma
Q3 ~ mu + 2/3 sigma
1 IQR ~ 4/3 sigma
1.5 IQR ~ 2 sigma
inner fence ~ mu +- 2 2/3 sigma which is about the 0.5 percentile.
-right so far -
and then burbled
The inner fences are selected
I wrote:
An obvious approach that would seem to give the advantages hoped for
from the focussed test without the disadvantages would be just to group
questions in the original test in roughly increasing order of
difficulty.
which, I think, answers Dennis' question.
I
As for the other examples, 'professional' as a noun was good enough
for Dickens. Milton (1671) uses 'academic' as a noun.
And Shakespeare, mechanical.
-Robert Dawson
=
Instructions for joining and
Gordon D. Pusch wrote:
[EMAIL PROTECTED] (Chike Ubah) writes:
ATTENTION:
Dear Sir,
This letter might surprise you because; we have not
met neither in person nor by correspondence. But I
believe it is one day that you get know somebody
either in physical or through
The focused test eliminates questions that would enable students to score A's,
B's, and C's. All they get is another chance to score a D rather than an F.
Implicit in the very concept of the focused test is the idea that a student who
fails the standard MCAS test cannot be more than a D
John Uebersax wrote:
Can anyone suggest a standalone Windows (or DOS) that produces
publication quality Venn diagrams?
...
The diagram should show the area of each circle as proportional its N,
and the overlap area as proprotional to the number of cases in both
groups.
Is this
Thom Baguley wrote:
however, I think the
defence of convenience samples can be stronger than this. Unless we
have reason to believe that a sample is biased in such a way as to
generate our pattern of results a convenience sample is just as
Silvert, Henry wrote:
I would like to add that with this kind of data [three-level ordinal]
we use the median instead of the average.
Might I suggest that *neither* is appropriate for most purposes? In
many ways, three-level ordinal data is like dichotomous data - though
there are a
Jon Cryer wrote:
I do not see how (probabilistic) inference is appropriate here at all.
Oh, it never is (strictly), outside of a few industrial
applications. Nobody ever took a random equal-probability sample from
all turnips, all cancer patients, all batches of stainless steel, all
Magenta wrote:
Robert J. MacG. Dawson [EMAIL PROTECTED] wrote in message
[EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
Can you do factor ananlysis, then? Probably yes.
...
Why a factor analysis and not a principal components analysis?
Dunno. But the interest
Herman Rubin wrote:
I consider the Fisherian one to be the only relevant one.
In fact, I do not think it goes far enough; at best,
probability is a property of the real world like length
and mass.
On the contrary: length and mass are abstractions that approximately
describe
KKARMA wrote:
As a teacher of research methodology in (music) education I am
interested in the relation between traditional statistics and the
bayesian approach. Bayesians claim that their approach is superior
compared with the traditional, for instance because it does not assume
normal
Chris wrote:
I know how to construct a confidence interval for a percentage when
there is a binomial (# of good units / # of total units) distribution.
How is the C.I. constructed if I have data such as the % of a liquid
evaporated for each of a number of batches and I want to know let's
J. Williams wrote:
On Mon, 09 Jul 2001 12:15:25 GMT, Jan Sjogren
[EMAIL PROTECTED] wrote:
Hi there!
I wonder what these things means:
SST
SSM
SSE
SSR
MSR
MSE
Thanks,
Janne
Are these statistical acronyms you want defined? SSt, for example,
could be total
Jay Warner wrote:
If the distribution is monomodal, not bounded (one peak, tails on both
sides), and within some rational range of a Normal, then a transformation
can be performed to make it look 'Normal.' See the Johnson transformation
in some commercial stat packages.
The next
beads... of three colors: red, yellow, and green.
seven-bead bracelets
three beads of any one color; two of a second color; two of a third.
And my count is:
(1) 3 choices for tripled color.
(2) EITHER the three beads are together, in which case the other 2 pairs
go into four adjacent
Elliot Cramer wrote:
I believe the point of the Danes
was that a placebo should be used in
research but that physicians should
?not?
think that they can cure people with
placebos; I agree.
-Robert Dawson
jim clark wrote:
Was there some reason that they did not include studies with only
2 groups: no treatment and placebo? Only those two groups are
necessary to determine whether placebo differs from no treatment.
Possibly because ethics committees would not OK an experiment that
Puzzle from last week:
That said, there IS at least one
natural application of such a
sampling technique [random selection
from equiprobable multisets], used in
a major industry, where it saves millions
of dollars a year.
Answer: The casino/gaming industry...
The wheel of
Alan McLean wrote:
Hi to all.
Can anyone tell me what is the distribution of the ratio of sample
variances when the ratio of population vriances is not 1, but some
specified other number?
*If* the population distributions are normal (and this is not a
robust assumption - in
Stanley110 wrote:
Ladies and Gentlemen,
What is the physical significance or meaning regarding a manufacturing process
whose output over an extended period of time has the same value for the
arithmetic, geometric and harmonic mean of a property, its purity, for
example? ... Or if any
Carl Huberty wrote:
Why do articles appear in print when study methods, analyses,
results, and conclusions are somewhat faulty?... I can think of two
reasons: 1) journal editors can not or do not send manuscripts to
reviewers with statistical analysis expertise; and 2) manuscript
David Heiser wrote:
We seem to have a lot of recent questions involving combinations, and
probabilities of combinations.
I've never seen multiset enumeration in elementary stats texts, perhaps
because it is not very useful as a sampling model. While a multiset can
certainly be the
Dale Glaser wrote:
Hi there..I have scoured my admittedly limited collection of probability
texts, and am stumped to find the answer to the following, so any help is
most appreciateda colleague just approached me with the following
problem at work: he wants to know the number of
Alan McLean wrote:
The p value is a direct measure of 'strength of evidence'.
and Lise DeShea responded:
I disagree. The p-value may be small when a
study has enormous power yet a small effect size.
A p-value by itself doesn't say much.
I don't think there's actually a
Paul W. Jeffries wrote:
What are
list members views on teaching students to use tables. In the computer
age, tables are an anachronism. The vast majority of students will never
use a t table.
Were it only so...
dennis roberts wrote:
as for the use of t tables ... or any other ...
1. one issue is can the student USE the table ... that is, you specify some
from the table and you want to know if they can find it
Yes. That is, in my experience, students, small dogs, and most white
Jon Cryer wrote:
These examples come the closest I have seen to having a known variance.
However, often measuring instruments, such as micrometers, quote their
accuracy as a percentage of the size of the measurement. Thus, if you
don't know the mean you also don't know the variance.
dennis roberts wrote:
the fundamental issue here is ... is it reasonably to expect ... that when
you are making some inference about a population mean ... that you will
KNOW the variance in the population?
No, Dennis, of course it isn't - at least in the social sciences and
Paul Swank wrote:
However, rather than do that why not right on to F? Why do t at all when you can do
anything with F that t can do plus a whole lot more?
Because the mean, normalized using the hypothesized mean and the
observed standard deviation, has a t distribution and not an F
Eric Bohlman wrote:
In science, it's not enough to
say that you have data that's consistent with your hypothesis; you also
need to show a) that you don't have data that's inconsistent with your
hypothesis and b) that your data is *not* consistent with
dennis roberts wrote:
the pragmatic of the situation is:
DO NOT SEND ANY ATTACHMENTS TO ANY LIST
More accurately - do not send any attachments to any list that does not
have a specific policy or tradition permitting this.
But, by the same token, a 10K attachment is no
dennis roberts wrote:
we have to first separate out 2 things:
1. some test statistics are naturally (the way they work anyway) ONE sided
with respect to retain/reject decisions
example: chi square test for independence ... we reject ONLY when chi
square is LARGER than some CV ... to
If the original cold fusion researchers had used proper statisti-
cal methods for detecting relationships (i.e., statistical tests,
a proper taking account of negative results, and experimental de-
sign considerations), it seems likely that the repeated high or
borderline p-values would
David Duffy wrote:
[EMAIL PROTECTED] wrote:
But Excel CAN produce simple scatter plots or bar charts. It is just that
the defaults are so horrible. With a lot of tweaking you can make them
My problem is cost. I want to get everyone in my department to have the
facility to produce
Radford Neal wrote:
In article [EMAIL PROTECTED],
James Ankeny [EMAIL PROTECTED] wrote:
... if the distribution is
heavily skewed to the right, say like income, why do we want an interval for
the population mean, when we are taught that the median is a better measure
of central
Will Hopkins wrote:
I accept that there are unusual cases where the null hypothesis has a
finite probability of being be true, but I still can't see the point in
hypothesizing a null, not in biomedical disciplines, anyway.
If only we could replace the p value with a probability that the
Bruce Weaver wrote:
Suppose you were conducting a test with someone who claimed to have ESP,
such that they were able to predict accurately which card would be turned
up next from a well-shuffled deck of cards. The null hypothesis, I think,
would be that the person does not have ESP. Is
James Ankeny wrote:
Hello,
I am currently taking a first course in statistics, and I was hoping that
perhaps someone might be kind enough to answer a question for me. I
understand that, while a quantitative variable may not be normally
distributed, we may calculate the mean of the
Shareef Siddeek wrote:
Then, what is the use of EXCEL?
EXCELlent question...
Joking apart, it can be a useful tool for preparing a downloaded dataset
for loading into a statistics program.
-Robert Dawson
=
Gene Gallagher wrote:
The scale is set from 200 to 280, but the maximum score that I've seen
so far is 257 (Boston Latin Math). The DOE only provides these data as
pdf's so it is difficult to find the max.
OK, so I didn't dream it. That leaves the question:
A histogram of a continuous variable is *not* primarily a graph of
counts within a range, but of densities; that is, an approximation to a
density function. Therefore, it is admissible to join or subdivide bars
provided that the area of the bar, not the height, represents the joint
"P.G.Hamer" wrote:
dennis roberts wrote:
there just is no good way to argue against the original choice C ... IN THE
CONTEXT OF THE STEM OF THE QUESTION
I am reminded of the joke article that contains many `politically incorrect'
answers to the exam question "given a barometer how
Here is the question:
Car A: 27.930.430.631.431.7
(a) If the manufactureres of car A want to advertise that their car
performed best in this test, which of the "average" discussed so far in
this chapter could they use to substantiate this claim?
Surely the
"Daniel P. B. Smith" wrote:
Can anybody possibly believe that a difference of one point in 245.3 can
possibly be significant? We're talking about schools with a less than a
maybe sixty fourth-graders in them. This just runs against common
sense...
Didn't somebody say a week or
At 10:41 AM -0400 16/1/01, Robert J. MacG. Dawson wrote:
There are those who would omit the word "small" from this; myself, I am
prepared to use a large data set as evidence of its own approximate
normality, largely because when the data set is large, "approximate
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