Hi
On Mon, 25 Feb 2002, Jay Tanzman wrote:
> I just got chewed out by my boss for modelling the means of some 7-point
> semantic differential scales. The scales were part of a written,
> self-administered questionnaire, and were laid out like this:
>
> Not stressful 1__ 2__ 3__ 4__ 5__ 6__ 7__
Hi
On 20 Feb 2002, Voltolini wrote:
> I was reading a definition of "experiment" in science to be used in a
> lecture and the use of treatments and controls are an important feature of
> an experiment but my doubt is... is it possible to plan an experiment
> without a control and call this a
Hi
On 8 Feb 2002, Thomas Souers wrote:
> 2) Secondly, are contrasts used primarily as planned
> comparisons? If so, why?
There are a great many possible contrasts even with a relatively
small number of means. If you examine the data and then decide
what contrasts to do, then you have in some i
Hi
On 30 Jan 2002, Wuzzy wrote:
> Anyway I'm currently going on the definition of "adjusted" for 1 2 and
> 3 as the following equation:
>
> adjusted variable=variable^-variable
>
> (where variable-hat represents the variable predicted by 1 2 and 3 in
> a multivariate equation and "variable" is
Hi
On Thu, 24 Jan 2002, Rich Ulrich wrote:
> On 24 Jan 2002 07:09:23 -0800, [EMAIL PROTECTED] (Rich Einsporn)
> wrote:
> > Jim Clark gave a fine answer to the question posed by Sangdon Lee.
> > However, I am curious about the correlation and R-square figures given by
> &
Hi
On 23 Jan 2002, Sangdon Lee wrote:
> I have one Y and two Xs (X1 and X2), and am trying to perform multiple
> linear regression. All Xs and Y variables are standardized (zero mean
> and unit variance). X1 and X2 are moderately correlated (r=0.6) and
> the correlation of X1 and X2 to Y is -0.
Hi
On Tue, 18 Dec 2001, Benjamin Kenward wrote:
> Let's say you have a repeatable experiment and each time the result can be
> classed into a number of discrete categories (in this real case, seven).
> If a treatment has no effect, it is known what the expected by chance
> distribution of results
Hi
On 6 Dec 2001, David Heiser wrote:
> Most of the focus is on structural equation modeling (SEM). For
> statisticians, a quick referral to Jim Steiger's article "Driving Fast in
> Reverse" in JASA March 2001, p331-p338 (if you have it around) is a quick
> discourse on SEM and the inherent probl
Hi
On 3 Dec 2001, Karl L. Wuensch wrote:
> I think that phrase has created much misunderstanding. I try
> to convince my students that correlation is necessary but not
> sufficient for establishing a causal relationship.
And I teach that NEITHER presence NOR absence of _simple_
correlation can
Hi
On Thu, 29 Nov 2001, Stan Brown wrote:
> But -- and in retrospect I should have seen it coming -- some
> students framed the hypotheses so that the alternative hypothesis
> was "the drug is effective as claimed." They had
> Ho: p <= .9; Ha: p > .9; p-value = .9908.
You might point out
Hi
On 28 Nov 2001, Dennis Roberts wrote:
> At 01:35 PM 11/28/01 -0600, jim clark wrote:
> >The distribution of grades will depend on the distribution of
> >difficulties of the items, one of the elements examined by
> >psychometrists in the development of professional-q
Hi
On Tue, 27 Nov 2001, Thom Baguley wrote:
> I'd argue that they probably aren't that independent. If I ask three
> questions all involving simple algebra and a student doesn't
> understand simple algebra they'll probably get all three wrong. In
> my experience most statistics exams are better r
Hi
On 25 Nov 2001, Herman Rubin wrote:
> If it is a good test, ability should predominate, and there is
> absolutely no reason for ability to even have close to a normal
> distribution. If one has two groups with different normal
> distributions, combining them will never get normality.
I think
Hi
On 16 Nov 2001, Rich Strauss wrote:
> I've just done some quick simulations in Matlab, constructing randomized
> null distributions of the t-statistic under both scenarious: (1) sample
> variances based on sample means vs. (2) variances about the pooled mean.
> Assuming I've done everything co
Hi
On Thu, 15 Nov 2001, 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?
What you are testing is whether there is more variability between
groups than you would ex
Hi
On 15 Nov 2001, dennis roberts wrote:
> in the moore and mccabe book (IPS), in the section on testing for
> differences in population proportions, when it comes to doing a 'z' test
> for significance, they argue for (and say this is commonly done) that the
> standard error for the differen
Hi
On 2 Nov 2001, Donald Burrill wrote:
> On Fri, 2 Nov 2001, jim clark wrote:
> > I would hate to ressurect a debate from sometime in the past
> > year, but the chi-squared is a non-directional (commonly referred
> > to as two-tailed) test, although it is true that you only
Hi
On Thu, 18 Oct 2001, Wouter Duyck wrote:
> Suppose i have a factorial design with two between-subject factors (one
> factor A of 3 levels and one factor B of 2 levels) en two within-subject
> factors (one factor C of 2 levels and one factor D of 5 levels). Of course,
> to perform an ANOVA on t
Hi
On 4 Oct 2001, Edwina Chappell wrote:
> Permutations versus Combinations. Easy ways to understand
> the concepts and distinguish when to use?
I use to like to teach both as a specific variant of the
partition rule, and then the distinction was whether specific
problems involved so many sets
Hi
On 26 Sep 2001, Burke Johnson wrote:
> R Pretest Treatment Posttest
> R PretestControl Posttest
> In the social sciences (e.g., see Pedhazur's popular
> regression text), the most popular analysis seems to be to
> run a GLM (this version is often called an ANCOVA), where Y
> is
Hi
On Thu, 20 Sep 2001, @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.
>
> Is this conceivable? for excel etc.
Easily done with various statistical software (e.g., SPSS, SAS),
if you have acces
Hi
I found the Rosenthal reference that addresses the following
point:
On 13 Sep 2001, Herman Rubin wrote:
> The effect size is NOT small, or it would not save more
> than a very small number of lives. If it were small,
> considering the dangers of aspirin, it would not be used
> for this purpo
Hi
On 13 Sep 2001, Herman Rubin wrote:
> jim clark <[EMAIL PROTECTED]> wrote:
> >Or consider a study with a small effect size that is significant.
> >The fact that the effect is significant indicates that some
> >non-chance effect is present and it m
Hi
On 13 Sep 2001, Rolf Dalin wrote:
> Hi, this is about Jim Clark's reply to dennis roberts.
> > I'm not sure how "both informative" gets translated into "neither
> > very informative." Seems like a perverse way of thinking to me.
> > Moreover, your original question was "then what benefit is
Hi
On 12 Sep 2001, dennis roberts wrote:
> At 07:23 PM 9/12/01 -0500, jim clark wrote:
> >What your table shows is that _both_ dimensions are informative.
> >That is, you cannot derive effect size from significance, nor
> >significance from effect size. To illustr
Hi
On 12 Sep 2001, Dennis Roberts wrote:
> given a simple effect size calculation ... some mean difference compared to
> some pooled group or group standard deviation ... is it not possible to
> obtain the following combinations (assuming some significance test is done)
>
>
Hi
On 21 Aug 2001, RFerreira wrote:
> The formula wich gives the Standard Deviation ,
> SD=((x-mean)^2/(n-1))^0.5 ,can be applied to Any data set. When we
> have that value we know two things about the set: The Mean and the SD.
> With this two values We can have one powerful intuitive use to the
Hi
On 27 Dec 2000, Jeff Rasmussen wrote:
> >scores, but not in aggregating them). In general, human judgment
> >does not fare all that well relative to actuarial (i.e.,
> >statistical) methods. Interesting that someone posting to a
> >statistical newsgroup would advocate the non-statistical ap
Hi
On Wed, 27 Dec 2000, T.S. Lim wrote:
> In article <[EMAIL PROTECTED]>,
> jim clark <[EMAIL PROTECTED]> wrote:
> > On Tue, 26 Dec 2000, John Uebersax wrote:
> > > IMHO, psychological tests in this case should not substitute for a
> > > thorough inte
Hi
On Tue, 26 Dec 2000, John Uebersax wrote:
> IMHO, psychological tests in this case should not substitute for a
> thorough interview and human judgment.
>
> Just my .02 worth.
There is a considerable literature on clinical judgment (i.e.,
interview and human judgement) vs. actuarial predictio
Hi
> On Fri, 29 Sep 2000, Lu=EDs Silva wrote:
> > For a certain variable I applied a Three Factor ANOVA and found a
> > significant interaction between two factors.=20
> > I have two levels for each factor. Then, I applied the HSD Tukey test=
=20
> > for multiple unplanned comparisons, in order
Hi
On 25 Apr 2000, Simon, Steve, PhD wrote:
> I'm helping out someone taking a Statistics class and her instructor is
> drawing a distinction between "part correlation" and "partial correlation".
> I had never heard of the term "part correlation" before.
As others have pointed out, part is synon
Hi
On 29 Feb 2000, Magill, Brett wrote:
> I am planning to design a study of an educational program. Of interest is
> the decay over time of knowledge and skills learned through the program.
> Specifically, we want to know if there is a point in time when the rate of
> decay changes (a steady dr
Hi
On Sat, 25 Dec 1999, Jerry Dallal wrote:
> Herman Rubin ([EMAIL PROTECTED]) wrote:
> : What is the purpose of homework? It should be to help learning,
> : and this cannot be combined with being used for a grade. Those
> : problems which do not contribute to learning are a waste of time.
Her
Hi
On Wed, 22 Dec 1999, Peter Westfall wrote:
> Jim Clark wrote:
> > Artificially giving all students (or almost all) the same grade
> > does not minimize variation in the underlying trait, achievement,
> > in this case. It simply hides the variation so that one does not
&g
Hi
On Tue, 21 Dec 1999, Peter Westfall wrote:
> Regarding making the standard deviation large, Deming would say that
> management's (professors, administrators) job entails minimizing
> variation among students. This can be done in the usual ways -
> admissions procedures, advising, prerequisite
HI
On 7 Dec 1999, Magill, Brett wrote:
> I am a graduate student in sociology studying individual's perceptions of
> control (locus of control) using existing data. The data set include four
> items to measure this construct which were taken from a larger scale of more
> than twenty, the larger
Hi
On 28 Nov 1999, Donald F. Burrill wrote:
> On Sun, 28 Nov 1999, Rich Ulrich wrote in part:
> > This is consistent with what Donald says, about the appearance of cell
> > means being disordinal once you have subtracted out the main effects
> > (so, why would you want to do that?).
>
> Most of
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