Date:         Thu, 1 Sep 2005 20:42:46 +0100
Reply-To:     starborn@statisticsdoc.com
Sender:       "SPSSX(r) Discussion" <SPSSX-L@LISTSERV.UGA.EDU>
From:         Keith Starborn <starborn@statisticsdoc.com>
Subject:      Re: MANOVA vs. Repeated Measures ANOVA
Comments: To: "Yampolskaya, Svetlana" <yampol@fmhi.usf.edu>
In-Reply-To:  <789FF757552CFF42A4A9A66306B331A24D69D9@xmail.fmhi.usf.edu>
Content-Type: text/plain; charset=ISO-8859-1; format="flowed"

Keith Starborn
www.statisticsdoc.com

Dear Lana,

Dr. Swanks' suggestion regarding Huberty and Morris (1989) is an excellent one
(as is the reference to Tabachnick & Fidellas by Dr. Buchanan).  Many journal
editors, and an entire generation of graduate students in Education and
behavioral sciences, have been socialized to believe that a significant MANOVA
is a necessary condition for conducting ANOVAs, that MANOVAs are needed
whenever a study has more than one dependent variable in order to guard
against
inflated alpha levels, and that the need for MANOVA is even greater when the
dependent variables are correlated.  These assumptions have been disputed most
notably by Huberty and Morris (1989) and others.

Having said that, you may or may not glean some interesting insights
from asking
multivariate questions of your data, along the lines discussed by Huberty and
Morris.  Do you consider your set of five dependent variables to measure a
complex of related school adjustment variables?  Are the program activities
ones that you would expect to impact on this set of school adjustment
variables?  Are you perhaps interested in the multivariate structure of the
relationships between program actitivities and change in multiple school
adjustment indices?

HTH,

KS

Quoting "Yampolskaya, Svetlana" <yampol@fmhi.usf.edu>:

> Dear List,
>
> I have 5 DV (i.e., student GPA, number of disciplinary referrals, days a
> student was absent from school, etc.). These DVs were measures twice
> (the beginning of the semester and at the end). My IV is level of
> participation in program activiteis.  I used Repeated Measures ANOVA.
> The reviewers of the manuscript made the following comment:
>
> Why MANOVAs (vs ANOVA) were not conducted to account for the
> correlations (relatedness) between dependent variables?
>
> Can anybody help and explain when it is more appropriate to use MANOVA
> vs ANOVA?
>
> Thank you in advance,
>
> Lana
>



--
For personalized and experienced statistical consulting,
visit www.statisticsdoc.com