Re: ANOVA QUESTION - Terminology


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

.

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