Re: ANOVA QUESTION - Terminology

I have looked at an intro to biostatistics book.

I know two groups is t-test and more than two is ANOVA. I'm sorry this
sounds so basic, but I didn't find any example of this in the book.
Most examples of ANOVA are 3 groups of race (Chinese, White, Black)
with one dependent variable (IQ). I can see how this is a one-way as
there is one independent and one dependent. When repeated measures is
described in the book, the ANOVA now changes to something like
monitoring heart rate at several times during biking. A two-way is
described as having two independent variables, say gender and race in
which IQ is again, the dependent variable.

The question I have is what would the analysis be for for what I was
suggesting above. To me you could treat it as a two-way in that Group
(A,B,C) and Test# (Pre Post) could serve as two independent variables,
but to me I thought it sounded like a repeated measures because the
Test Score was the dependent variable measured at two time points.
There is no example like this in my book, and perhaps I not understand
it. I would imagine this newsgroup is for individuals of all learning
levels?

To me, this sounds like a two-way design, but I am confused because it
is more like a one-way repeated measures since the dependent variable
is measured twice and there is the independent variable Group. I would
really like to know if this distinction.


Reef Fish wrote:
jp wrote:
If you perform a t-test on the change (difference from pre and post)
don't you have to look at the initial scores to see if they were
different?

I was really more concerned with the terminology.

That's why I suggested you get an elementary text book and read up
on the comparison of means.

Two groups; generally a T-test. More than two, the comparison of
MEANS is called, strangely, the ANOVA (analysis of VARIANCE).
Then you go on to other forms of ANOVA and designs.

The newsgroup is not where you can, or want to, learn the basics from
scratch. JMHO.

-- Reef Fish Bob.



Say I wanted to
compare the same dependent variable (pre and post scores), and I have
one independent variable (Group- A, B, C). I can see if I use the
differences between the pre and post this would be a simple one-way
with repeated measures. Assuming I don't use the differences what
would this be called, a two-way? That is, treating Group and Score as
independent variables?

Thanks for the responses!

Reef Fish wrote:
Richard Ulrich wrote:
On 9 Sep 2006 12:53:19 -0700, "jp" <jpopovich@xxxxxxxxx> wrote:

I have the following set up:

One group (males, females)
One dependent variable (test scores), but tested pre and post tutoring.

Would this be a repeated measures design?

It can be analyzed that way, with the two periods.

The two periods are pre-tutor score and post-tutor scores and
it has only ONE variable, of the "difference" (improvement).


What would this be called (i.e., One-way ANOVA with repeated measures,
Two-way, etc.)?

For Pre-Post, the testing usually assumes that the group means do
not differ at Pre;

Why? Where did you get that?

and the efficient test is usually the one-way
ANCOVA, using the Pre as covariate.

That's just a simple T-test for two independent groups on the
DIFFERENCE of the pre-and-post scores. Freshman/sophomore
stuff, Richard.

jp, get you an elementary testbook on testing means.

That may save you much time in unlearning some bad advice you
get from these newsgroups.

-- Reef Fish Bob.



For the repeated measures, it is "one-way" ANOVA with repeated
measures.

In general, a repeated-measures analysis with several
periods might have a few 'missings' and you could do
the closest thing to the same analysis by doing a two-way
ANOVA with Period and Subject (or ID) as the factors.


--
Rich Ulrich, wpilib@xxxxxxxx
http://www.pitt.edu/~wpilib/index.html

.

Relevant Pages

  • Re: ANOVA QUESTION - Terminology
    ... MEANS is called, strangely, the ANOVA. ... -- Reef Fish Bob. ... a repeated-measures analysis with several ...
    (sci.stat.consult)
  • Re: ANOVA QUESTION - Terminology
    ... I know two groups is t-test and more than two is ANOVA. ... But that is usually done in LINEAR MODELS after the introduction ... and Test# could serve as two independent variables, ... a repeated-measures analysis with several ...
    (sci.stat.consult)
  • Re: ANOVA QUESTION - Terminology
    ... If you perform a t-test on the change ... a repeated-measures analysis with several ...
    (sci.stat.consult)
  • Re: ANOVA QUESTION - Terminology
    ... Most examples of ANOVA are 3 groups of race ... and Test# could serve as two independent variables, ... measures design, probably because the procedure they use in their stats package is found under "GLM->Repeated Measures", or something similar. ... The interaction F-test is equivalent to an independent groups t-test on the change scores. ...
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