Sample size question
Can anyone point me to software for estimating ANCOVA or regression sample sizes based on effect size? Karen Scheltema Statistician HealthEast Research and Education 1700 University Ave W St. Paul, MN 55104 (651) 232-5212 fax (651) 641-0683 [EMAIL PROTECTED] = Instructions for joining and leaving this list and remarks about the problem of INAPPROPRIATE MESSAGES are available at http://jse.stat.ncsu.edu/ =
RE: Sample size question
G*Power is a powere analysis package that is freely available. You can download it at: http://www.psychologie.uni-trier.de:8000/projects/gpower.html You can calculate a sample size for a given effect size, alpha level, and power value. -Original Message- From: Scheltema, Karen [mailto:[EMAIL PROTECTED]] Sent: Friday, February 23, 2001 10:07 AM To: [EMAIL PROTECTED] Subject: Sample size question Can anyone point me to software for estimating ANCOVA or regression sample sizes based on effect size? Karen Scheltema Statistician HealthEast Research and Education 1700 University Ave W St. Paul, MN 55104 (651) 232-5212 fax (651) 641-0683 [EMAIL PROTECTED] = Instructions for joining and leaving this list and remarks about the problem of INAPPROPRIATE MESSAGES are available at http://jse.stat.ncsu.edu/ = = Instructions for joining and leaving this list and remarks about the problem of INAPPROPRIATE MESSAGES are available at http://jse.stat.ncsu.edu/ =
Re: Summary: Patenting a statistical innovation
"T.S. Lim" wrote: > > Thanks much to all who have replied. Algorithms and software can > be and have been patented (at least in the US). It appears that > major statistical societies have no explicit guidelines regarding > patent (?). Just hope that patenting statistical innovations won't > become a new trend. Same here. Radford Neal wrote: > Patents may seem like a good idea in theory, but the practice has > become horrible. See http://www.bustpatents.com/ for ample documentation of the above. The "Patent Newsletter" distributed from this site via e-mail is one of the few newsletters (if not the only one) that I actually read. -- Petr _ P e t r K u z m i c, Ph.D. mailto:[EMAIL PROTECTED] BioKin Ltd. * Software and Consulting http://www.biokin.com 1652 S. Grand Ave. Ste. 337(509) 334-4131 Pullman, WA 99163 fax (509) 332-3493 = Instructions for joining and leaving this list and remarks about the problem of INAPPROPRIATE MESSAGES are available at http://jse.stat.ncsu.edu/ =
Re: On inappropriate hypothesis testing. Was: MIT Sexism & statistical bunk
In article <[EMAIL PROTECTED]>, Rich Ulrich <[EMAIL PROTECTED]> wrote: > I agree, if you don't have "statistical power," then you don't ask > for a 5% test, or (maybe) any test at all. The JUSTIFICATION for > having a test on the MIT data is that the power is sufficient to say > something. The reason why one should NOT do a significance test on this data, at any level, and regardless of how much power the test would have, was explained by me a while ago in the post I have repeated below. If you think there is something wrong with my reasoning, I suggest you explain the flaw. Radford Neal -- I think the statistical issue in this discussion can be boiled down to a question of how to calculate standard errors for regression coefficients. What regression? Well, there isn't one, because there isn't any data, but the discussions seems to presuppose the possibility of data that for each faculty member gives their salary (the response variable, y), their gender (x1, coded as a dummy variable), and some indicator of performance (x2). The question is whether one has evidence that the regression coefficient for the dummy gender variable (x1) is non-zero. This will require computing the standard error for the estimate of this regression coefficient. The accepted procedure for computing this standard error involves the sample correlation between the two predictors, x1 and x2. When the sample correlation is high, the standard errors for the regression coefficients will tend to be high, making it more difficult to conclude that the coefficient for gender is non-zero. The procedure apparently being advocated by some posters is to perform a test of the null hypothesis that the correlation between x1 and x2 in the population is zero, and if there is not sufficient evidence to reject this null hypothesis, compute the standard errors for the regression coefficients as if the predictors were uncorrelated. I believe that this procedure is not generally accepted, for very good reasons. Radford M. Neal [EMAIL PROTECTED] Dept. of Statistics and Dept. of Computer Science [EMAIL PROTECTED] University of Toronto http://www.cs.utoronto.ca/~radford = Instructions for joining and leaving this list and remarks about the problem of INAPPROPRIATE MESSAGES are available at http://jse.stat.ncsu.edu/ =
RE: Sample size question
Thanks! This was exactly what I was looking for! Karen Scheltema Statistician HealthEast Research and Education 1700 University Ave W St. Paul, MN 55104 (651) 232-5212 fax (651) 641-0683 [EMAIL PROTECTED] > -Original Message- > From: Magill, Brett [SMTP:[EMAIL PROTECTED]] > Sent: Friday, February 23, 2001 9:53 AM > To: 'Scheltema, Karen'; [EMAIL PROTECTED] > Subject: RE: Sample size question > > G*Power is a powere analysis package that is freely available. You can > download it at: > > http://www.psychologie.uni-trier.de:8000/projects/gpower.html > > You can calculate a sample size for a given effect size, alpha level, and > power value. > > > -Original Message- > From: Scheltema, Karen [mailto:[EMAIL PROTECTED]] > Sent: Friday, February 23, 2001 10:07 AM > To: [EMAIL PROTECTED] > Subject: Sample size question > > > Can anyone point me to software for estimating ANCOVA or regression sample > sizes based on effect size? > > Karen Scheltema > Statistician > HealthEast > Research and Education > 1700 University Ave W > St. Paul, MN 55104 > (651) 232-5212 fax (651) 641-0683 > [EMAIL PROTECTED] > > > > = > Instructions for joining and leaving this list and remarks about > the problem of INAPPROPRIATE MESSAGES are available at > http://jse.stat.ncsu.edu/ > = = Instructions for joining and leaving this list and remarks about the problem of INAPPROPRIATE MESSAGES are available at http://jse.stat.ncsu.edu/ =
Re: Sample size question
You can use Sample Power from SPSS (a.k.a. Power and Preceision) or PASS 2000 from NCSS. For more info, please visit: http://www.spss.com http://www.ncss.com http://seamonkey.ed.asu.edu/~alex/teaching/WBI/power_es.html --- --"Regression to the mean" is not always true. After 30, my weight never regresses to the mean. Chong-ho (Alex) Yu, Ph.D., MCSE, CNE Academic Research Professional/Manager Educational Data Communication, Assessment, Research and Evaluation Farmer 418 Arizona State University Tempe AZ 85287-0611 Email: [EMAIL PROTECTED] URL:http://seamonkey.ed.asu.edu/~alex/ = Instructions for joining and leaving this list and remarks about the problem of INAPPROPRIATE MESSAGES are available at http://jse.stat.ncsu.edu/ =
Re: Sample size question
"Scheltema, Karen" wrote: > Can anyone point me to software for estimating ANCOVA or regression sample > sizes based on effect size? Look here: http://www.interchg.ubc.ca/steiger/r2.htm Chuck -<>-<>-<>-<>-<>-<>-<>-<>-<>-<>-<>-<>-<>-<>-<>-<>- Chuck Cleland Institute for the Study of Child Development UMDNJ--Robert Wood Johnson Medical School 97 Paterson Street New Brunswick, NJ 08903 phone: (732) 235-7699 fax: (732) 235-6189 http://www2.umdnj.edu/iscdweb/ http://members.nbci.com/cmcleland/ -<>-<>-<>-<>-<>-<>-<>-<>-<>-<>-<>-<>-<>-<>-<>-<>- = Instructions for joining and leaving this list and remarks about the problem of INAPPROPRIATE MESSAGES are available at http://jse.stat.ncsu.edu/ =
RE: Sample size question
I tried the site but received errors trying to download it. It couldn't find the FTP site. Has anyone else been able to access it? Karen Scheltema Statistician HealthEast Research and Education 1700 University Ave W St. Paul, MN 55104 (651) 232-5212 fax (651) 641-0683 [EMAIL PROTECTED] > -Original Message- > From: Chuck Cleland [SMTP:[EMAIL PROTECTED]] > Sent: Friday, February 23, 2001 11:04 AM > To: [EMAIL PROTECTED] > Subject: Re: Sample size question > > "Scheltema, Karen" wrote: > > Can anyone point me to software for estimating ANCOVA or regression > sample > > sizes based on effect size? > > Look here: > > http://www.interchg.ubc.ca/steiger/r2.htm > > Chuck > > -<>-<>-<>-<>-<>-<>-<>-<>-<>-<>-<>-<>-<>-<>-<>-<>- > Chuck Cleland > Institute for the Study of Child Development > UMDNJ--Robert Wood Johnson Medical School > 97 Paterson Street > New Brunswick, NJ 08903 > phone: (732) 235-7699 >fax: (732) 235-6189 > http://www2.umdnj.edu/iscdweb/ > http://members.nbci.com/cmcleland/ > -<>-<>-<>-<>-<>-<>-<>-<>-<>-<>-<>-<>-<>-<>-<>-<>- > > > = > Instructions for joining and leaving this list and remarks about > the problem of INAPPROPRIATE MESSAGES are available at > http://jse.stat.ncsu.edu/ > = = Instructions for joining and leaving this list and remarks about the problem of INAPPROPRIATE MESSAGES are available at http://jse.stat.ncsu.edu/ =
pizza
let's say that you have 'students' (they love pizza you know!) who claim they can easily tell the difference between brands of pizza (pizza hut, dominoes, etc.) ... so, you put them up to the challenge you select 10 students at random ... and, arrange a taste test as follows: you have some piping hot pizzas ... from dominoes and pizza hut ... and, you cut slices of each (pepperoni and green peppers in all cases) and, when each student comes in ... you randomly pick 2 slices from one of the two brands ... and 1 from the other brand ... and lay them out in front of the student in a random order and ask the student to taste test ... then tell you which two of the 3 are the same ... and which 1 of the 3 is different ... of course, they have to try all 3 ... and, probably go back and forth retasting more than once before making their final decision ... now, we have 10 trials in terms of students doing independent tests, one from the other ... in each of these 10 cases ... if the identification of the 3 is correct ... you count this as a successful identification ... if there are any misplacements or misidentifications ... then we label this as a failure ... say we have pizza 1, 2, and 3 ... and the only allowable options are: 12 same, 3 different 13 same, 2 different 23 same, 1 different that is, the instructions are such that they are told ... 2 ARE the same ... and, 1 IS different so, saying all are the same ... or all are different ... are not options that you allow for the taster so, in this scenario, there are 10 independent trials ... but, what is really the p for success? q for failure? is this situation of n=10 ... really a true binomial case where p for success is 1/3 under the assumption that simple guessing were the way in which tasters made their decisions? (as an aside, what would it mean for tasters in this situation to be making their decisions purely based on chance?) _ dennis roberts, educational psychology, penn state university 208 cedar, AC 8148632401, mailto:[EMAIL PROTECTED] http://roberts.ed.psu.edu/users/droberts/drober~1.htm = Instructions for joining and leaving this list and remarks about the problem of INAPPROPRIATE MESSAGES are available at http://jse.stat.ncsu.edu/ =
Rice statistic
Hallo I am new, my problem is simple but I have not found a solution:.. I spoke with a lot of professors of my University, but without results. the problem is: suppose you have the follow process: A+x+i*y where A is a real positive constant while x and y are gaussian random variates with null mean and variance sigma , therefore x and y are indipendents. i is sqrt(-1) . if you compute the abs(A+x+i*y) you have for this new variabile a statistic named Rice statistic, now what is the mean and the variance of this statistic if I compute angle(A+x+i*y) what is the statistic of this variabile??? This is a problem most common in radar theory but the only solutions I have found are for A=0 in which case abs(x+i*y) is a rayleigh statistic while angle(x+i*y) is uniformly distribuited between -pi and pi. Thank in advance please write to [EMAIL PROTECTED] = Instructions for joining and leaving this list and remarks about the problem of INAPPROPRIATE MESSAGES are available at http://jse.stat.ncsu.edu/ =
Time series analysis with Excel macro
C'est un message de format MIME en plusieurs parties. --=_NextPart_000_0012_01C09DDD.8A717B00 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Is there a site where I can download an Excel macro that would enable me = to analyse a time series with the ARIMA Box-Jenkins method ? --=_NextPart_000_0012_01C09DDD.8A717B00 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Is there a site where I can download an Excel macro = that would=20 enable me to analyse a time series with the ARIMA = Box-Jenkins method=20 ? --=_NextPart_000_0012_01C09DDD.8A717B00-- = Instructions for joining and leaving this list and remarks about the problem of INAPPROPRIATE MESSAGES are available at http://jse.stat.ncsu.edu/ =
Re: pizza
On Fri, 23 Feb 2001, dennis roberts wrote: > > but, what is really the p for success? q for failure? > > is this situation of n=10 ... really a true binomial case where p for > success is 1/3 under the assumption that simple guessing were the way in > which tasters made their decisions? It's late on friday so I could be missing something, but it seems reasonable that p = 1/3 in this case. If the taster were to simply walk into the room and point at the middle piece of pizza each trial they should be right 1 time in 3. (Unless there is some experimental manipulation that keeps the odd piece in one position more frequently than would be expected...but I think you specified counterbalancing in your question.) > > (as an aside, what would it mean for tasters in this situation to be making > their decisions purely based on chance?) I would interpret it as meaning that the tasters couldn't tell the two pizza brands apart. They did no better than someone who didn't taste the pizza and so were unable to discriminate between to two brands. The obivious explanations are that the pizza brands really are the same in all ways that matter for taste discrimination, or the tasters were not very good at the task. Michael > > _ > dennis roberts, educational psychology, penn state university > 208 cedar, AC 8148632401, mailto:[EMAIL PROTECTED] > http://roberts.ed.psu.edu/users/droberts/drober~1.htm > > > > = > Instructions for joining and leaving this list and remarks about > the problem of INAPPROPRIATE MESSAGES are available at > http://jse.stat.ncsu.edu/ > = > *** Michael M. Granaas Associate Professor[EMAIL PROTECTED] Department of Psychology University of South Dakota Phone: (605) 677-5295 Vermillion, SD 57069 FAX: (605) 677-6604 *** All views expressed are those of the author and do not necessarily reflect those of the University of South Dakota, or the South Dakota Board of Regents. = Instructions for joining and leaving this list and remarks about the problem of INAPPROPRIATE MESSAGES are available at http://jse.stat.ncsu.edu/ =
RE: Sample size question
>I tried the site but received errors trying to download it. It couldn't >find the FTP site. Has anyone else been able to access it? > >Karen Scheltema >Statistician >HealthEast >Research and Education >1700 University Ave W >St. Paul, MN 55104 >(651) 232-5212 fax (651) 641-0683 >[EMAIL PROTECTED] > >> -Original Message- >> From:Chuck Cleland [SMTP:[EMAIL PROTECTED]] >> Sent:Friday, February 23, 2001 11:04 AM >> To: [EMAIL PROTECTED] >> Subject: Re: Sample size question >> >> "Scheltema, Karen" wrote: >> > Can anyone point me to software for estimating ANCOVA or regression >> sample >> > sizes based on effect size? >> >> Look here: >> >> http://www.interchg.ubc.ca/steiger/r2.htm >> >> Chuck > Karen, I just looked, and was able to access the site and download the files. Dan Nordlund = Instructions for joining and leaving this list and remarks about the problem of INAPPROPRIATE MESSAGES are available at http://jse.stat.ncsu.edu/ =
Re: Sample size question
On 23 Feb 2001 12:08:45 -0800, [EMAIL PROTECTED] (Scheltema, Karen) wrote: > I tried the site but received errors trying to download it. It couldn't > find the FTP site. Has anyone else been able to access it? As of a few minutes ago, it downloaded fine for me, when I clicked on it with Internet Explorer. The .zip file expanded okay. I used right-click (I just learned that last week) in order to download the .pfd version of the help. [ ... ] < Earlier Q and Answer > "Can anyone point me to software for estimating ANCOVA or regression sample sizes based on effect size?" > > Look here: > > http://www.interchg.ubc.ca/steiger/r2.htm Hmm. Placing limits on R^2. I have't read the accompanying documentation. On the general principal that you can't compute power if you don't know what power you are looking for, I suggest reading the relevant chapters in Jacob Cohen's book (1988+ edition). -- Rich Ulrich, [EMAIL PROTECTED] http://www.pitt.edu/~wpilib/index.html = Instructions for joining and leaving this list and remarks about the problem of INAPPROPRIATE MESSAGES are available at http://jse.stat.ncsu.edu/ =
Re: pizza
a concern i have in this situation ... and why i posed the question is as follows since it is a taste test ... Ss will taste the pizzas ... so, the notion of just selecting ONE and saying it is different seems not a reasonble scenario so, what would a resonable guessing scenario be? one might be that ... after tasting and retasting ... the S says to himself/herself ... i just cannot make a choice ... i really don't know the difference ... BUT, he/she has to make a choice ... those are the rules ... so, if that were the case ... let's say that the strategy he/she adopts is to flip a mental coin ... if it is heads, call the first pizza SAME ... and, if tails ... call it DIFFERENT ... now, if the first turns up heads ... then there is another piece to do the mental flip for ... so the second piece gets the second flip ... assume it too is heads ... and is therefore called SAME ... then, there is NO random choice for the third ... it has to be DIFFERENT ... the third slice decision in this case is NOT independent of the second ... but, what if the first slice mental flip came up TAILS ... then for it, it is called the different one ... but automatically and out of the control of the S are the decisions for the other two ... they are both SAMES i claim that in this situation ... the decisions for all three are NOT independent decisions ... therefore, it does not satisfy one of the conditions for the binomial to be a correct model ... if the strategy were to simply flip a three sided coin ... with sides pizza slice 1, 2, or 3 ... whichever one the mental flip lands on ... the OTHER two are fixed choices and out of the control of the S ... some of the choices DEPEND on what has already transpired At 03:00 PM 2/23/01 -0600, Mike Granaas wrote: >On Fri, 23 Feb 2001, dennis roberts wrote: > > >> >> but, what is really the p for success? q for failure? >> >> is this situation of n=10 ... really a true binomial case where p for >> success is 1/3 under the assumption that simple guessing were the way in >> which tasters made their decisions? > >It's late on friday so I could be missing something, but it seems >reasonable that p = 1/3 in this case. If the taster were to simply walk >into the room and point at the middle piece of pizza each trial they >should be right 1 time in 3. (Unless there is some experimental >manipulation that keeps the odd piece in one position more frequently than >would be expected...but I think you specified counterbalancing in your >question.) > >> >> (as an aside, what would it mean for tasters in this situation to be making >> their decisions purely based on chance?) > >I would interpret it as meaning that the tasters couldn't tell the two >pizza brands apart. They did no better than someone who didn't taste the >pizza and so were unable to discriminate between to two brands. The >obivious explanations are that the pizza brands really are the same in all >ways that matter for taste discrimination, or the tasters were not very >good at the task. > >Michael > >> >> _ >> dennis roberts, educational psychology, penn state university >> 208 cedar, AC 8148632401, mailto:[EMAIL PROTECTED] >> http://roberts.ed.psu.edu/users/droberts/drober~1.htm >> >> >> >> = >> Instructions for joining and leaving this list and remarks about >> the problem of INAPPROPRIATE MESSAGES are available at >> http://jse.stat.ncsu.edu/ >> = >> > >*** >Michael M. Granaas >Associate Professor[EMAIL PROTECTED] >Department of Psychology >University of South Dakota Phone: (605) 677-5295 >Vermillion, SD 57069 FAX: (605) 677-6604 >*** >All views expressed are those of the author and do not necessarily >reflect those of the University of South Dakota, or the South >Dakota Board of Regents. > > == dennis roberts, penn state university educational psychology, 8148632401 http://roberts.ed.psu.edu/users/droberts/drober~1.htm = Instructions for joining and leaving this list and remarks about the problem of INAPPROPRIATE MESSAGES are available at http://jse.stat.ncsu.edu/ =
Type III errors
Recently there was a discussion here involving the phrase "Type III errors." I noted that others have used that phrase to mean inferring the incorrect direction of effect after rejecting a nondirectional hypothesis, but I was unable to give references. This week I stumbled across references to such use of the term. Interested parties may consult the article by Leventhal and Huynh (Psychological Methods, 1996, 1, 278-292). They recommend that the probability of making a Type III error be subtracted from the probability of correctly rejecting the nondirectional null when computing power (since it is common practice to infer a direction of effect following rejection of a nondirectional null. I have posted a summary of the article at: http://core.ecu.edu/psyc/wuenschk/StatHelp/Type_III.htm +Karl L. Wuensch, Department of Psychology,East Carolina University, Greenville NC 27858-4353Voice: 252-328-4102 Fax: 252-328-6283[EMAIL PROTECTED] http://core.ecu.edu/psyc/wuenschk/klw.htm
Dr. H.A. David ' article about central tendency in ISI Review
Dr. H.A. David published an article in ISI Review on a historical background on central tendency of data.More details about this article or who coined the word" mean/median/mode" would be very much appreciated. Jineshwar Singh Business Department George Brown College St .James campus [EMAIL PROTECTED] * You cannot control how others act but you can control how you react. 416 -415-2089 http://www.gbrownc.on.ca/~jsingh = Instructions for joining and leaving this list and remarks about the problem of INAPPROPRIATE MESSAGES are available at http://jse.stat.ncsu.edu/ =
