Re: When to Use t and When to Use z Revisited

2001-12-10 Thread kjetil halvorsen
Ronny Richardson wrote: A few weeks ago, I posted a message about when to use t and when to use z. In reviewing the responses, it seems to me that I did a poor job of explaining my question/concern so I am going to try again. I have included a few references this time since one

Re: When to Use t and When to Use z Revisited

2001-12-10 Thread Dennis Roberts
At 04:14 AM 12/10/01 +, Jim Snow wrote: Ronny Richardson [EMAIL PROTECTED] wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... A few weeks ago, I posted a message about when to use t and when to use z. I did not see the earlier postings, so forgive me if I repeat advice already

Re: When to Use t and When to Use z Revisited

2001-12-10 Thread Gus Gassmann
Dennis Roberts wrote: this is pure speculation ... i have yet to hear of any convincing case where the variance is known but, the mean is not What about that other application used so prominently in texts of business statistics, testing for a proportion?

Re: When to Use t and When to Use z Revisited

2001-12-10 Thread Jon Cryer
But then you should use a binomial (or hypergeometric) distribution. Jon Cryer p.s. Of course, you might approximate by an appropriate normal distribution. At 11:39 AM 12/10/01 -0400, you wrote: Dennis Roberts wrote: this is pure speculation ... i have yet to hear of any convincing case where

Re: When to Use t and When to Use z Revisited

2001-12-10 Thread Jerry Dallal
Dennis Roberts wrote: this is pure speculation ... i have yet to hear of any convincing case where the variance is known but, the mean is not A scale (weighing device) with known precision. = Instructions for joining and

Re: When to Use t and When to Use z Revisited

2001-12-10 Thread Jon Cryer
I always thought that the precision of a scale was proportional to the amount weighed. So don't you have to know the mean before you know the standard deviation? But wait a minute - we are trying assess the size of the mean! Jon Cryer At 03:42 PM 12/10/01 +, you wrote: Dennis Roberts wrote:

Re: Cramer-von-Mises Criterion

2001-12-10 Thread Clay S. Turner
You have probably thought of this, but the age old standard is the Chi Square test. One thing about empirical distributions is that they may not be one of the standard forms. This is why the Jackknife method and then later the Bootstrapping methods were developed. Thus you can extract the

Re: When to Use t and When to Use z Revisited

2001-12-10 Thread Art Kendall
the sample mean of the dichotomous (one_zero, dummy) variable is known, It is the proportion. Gus Gassmann wrote: Dennis Roberts wrote: this is pure speculation ... i have yet to hear of any convincing case where the variance is known but, the mean is not What about that other

Re: When to Use t and When to Use z Revisited

2001-12-10 Thread Gus Gassmann
Art Kendall wrote: (putting below the previous quotes for readability) Gus Gassmann wrote: Dennis Roberts wrote: this is pure speculation ... i have yet to hear of any convincing case where the variance is known but, the mean is not What about that other application used so

Re: When to Use t and When to Use z Revisited

2001-12-10 Thread Art Kendall
Usually I would use software. As I tried to show is the sample syntax I posted earlier, it doesn't usually make much difference whether you use z or t. Gus Gassmann wrote: Art Kendall wrote: (putting below the previous quotes for readability) Gus Gassmann wrote: Dennis Roberts

Re: Cramer-von-Mises Criterion

2001-12-10 Thread Chia C Chong
Hi!! Thanks for your reply...do you mean that Jackknife and Bootstrapping methods area also some kind of goodness-of-fit tests?? Cheers, CCC Clay S. Turner [EMAIL PROTECTED] wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... You have probably thought of this, but the age old

Re: Cramer-von-Mises Criterion

2001-12-10 Thread Clay S. Turner
Hello Chia, No actually they are used to extract the distribution from the data. They do this by a process known as resampling. Clay Chia C Chong wrote: Hi!! Thanks for your reply...do you mean that Jackknife and Bootstrapping methods area also some kind of goodness-of-fit

What is the difference between Statistics and Mathematical Statistics?

2001-12-10 Thread Andreas Karlsson
What is (are) the difference(s) between Statistics and Mathematical Statistics? = Instructions for joining and leaving this list and remarks about the problem of INAPPROPRIATE MESSAGES are available at

Re: When to Use t and When to Use z Revisited

2001-12-10 Thread Jon Cryer
Only as an approximation. At 12:57 PM 12/10/01 -0400, you wrote: Art Kendall wrote: (putting below the previous quotes for readability) Gus Gassmann wrote: Dennis Roberts wrote: this is pure speculation ... i have yet to hear of any convincing case where the variance is known

Re: What is the difference between Statistics and Mathematical Statistics?

2001-12-10 Thread Kevin C. Heslin
Mathematical statistics will require that you take 5, rather than 2, Advil or Tylenol. At 06:24 PM 12/10/2001 +, Andreas Karlsson wrote: What is (are) the difference(s) between Statistics and Mathematical Statistics? =

Re: When to Use t and When to Use z Revisited

2001-12-10 Thread Dennis Roberts
At 03:42 PM 12/10/01 +, Jerry Dallal wrote: Dennis Roberts wrote: this is pure speculation ... i have yet to hear of any convincing case where the variance is known but, the mean is not A scale (weighing device) with known precision. as far as i know ... knowing the precision is

Re: Slutsky's theorem

2001-12-10 Thread Herman Rubin
In article [EMAIL PROTECTED], kjetil halvorsen [EMAIL PROTECTED] wrote: Slutsky's theorem says that if Xn -(D) X and Yn -(P) y0, y0 a constant, then Xn + Yn -(D) X+y0. It is easy to make a counterexample if both Xn and Yn converges in distribution. Anybody have an counterexample when Yn

Re: When to Use t and When to Use z Revisited

2001-12-10 Thread Rich Ulrich
On Mon, 10 Dec 2001 12:57:29 -0400, Gus Gassmann [EMAIL PROTECTED] wrote: Art Kendall wrote: (putting below the previous quotes for readability) Gus Gassmann wrote: Dennis Roberts wrote: this is pure speculation ... i have yet to hear of any convincing case where the

test-ignore

2001-12-10 Thread Jim Snow
test please ignore = Instructions for joining and leaving this list and remarks about the problem of INAPPROPRIATE MESSAGES are available at http://jse.stat.ncsu.edu/

Re: Sorry for question, but how is the english word for @

2001-12-10 Thread Richard Wright
The name given to the symbol @ in international standard character sets is 'commercial at'. See http://www.quinion.com/words/articles/whereat.htm for a history of the symbol. Richard Wright On Mon, 10 Dec 2001 23:34:19 +0100, Nathaniel [EMAIL PROTECTED] wrote: Hi, Sorry for question, but

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Re: Sorry for question, but how is the english word for @

2001-12-10 Thread Art Kendall
atusually indicate some kind of rate or unit price 10 pounds @ $1 per pound on the net is is used as a separator between the id of an individual and his/her location [EMAIL PROTECTED] id spoken as john dot smith at harvard dot e d u. until the early-80's or so dot was spoken as point as

RE: Question about concatenating probability distributions

2001-12-10 Thread David Heiser
RE: The Poisson process and Lognormal action time. This kind of problem arises a lot in the actuarial literature (a process for the number of claims and a process for the claim size), and the Poisson and the lognormal have been used in this context - it might be worth your while to look there

Re: When to Use t and When to Use z Revisited

2001-12-10 Thread Vadim and Oxana Marmer
besides, who needs those tables? we have computers now, don't we? I was told that there were tables for logarithms once. I have not seen one in my life. Is not it the same kind of stuff? 3. Outdated. on the grounds that when sigma is unknown, the proper distribution is t (unless N is

Re: When to Use t and When to Use z Revisited

2001-12-10 Thread Vadim and Oxana Marmer
3) When n is greater than 30 and we do not know sigma, we must estimate sigma using s so we really should be using t rather than z. you are wrong. you use t-distribution not because you don't know sigma, but because your statistic has EXACT t-distribution under certain conditions. I know that

Re: When to Use t and When to Use z Revisited

2001-12-10 Thread Vadim and Oxana Marmer
Sigma is hardly ever known, so you must use t. Then why not simply tell the students: use the t table as far as it goes, (usually around n=120), and after that, use the n=\infty line (which corresponds to the normal distribution). Then there is no need for a rule for when to use z, when to