Date:         Fri, 17 Dec 2010 20:28:00 -0500
Reply-To:     R B <ryan.andrew.black@gmail.com>
Sender:       "SPSSX(r) Discussion" <SPSSX-L@LISTSERV.UGA.EDU>
From:         R B <ryan.andrew.black@gmail.com>
Subject:      Re: Can I use time and gender as covariates in Ancova?
In-Reply-To:  <1292428359532-3306510.post@n5.nabble.com>
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Petter,

In addition to the advice you have received thus far, let me suggest
you consider employing a linear MIXED model instead of an general
linear model. I am making this suggestion since each participant was
measured on the outcome of interest three times. It isn't uncommon to
observe residuals obtained from observations closer in time to be more
highly correlated than residuals obtained from more distant
observations. Thus, an autoregressive residual correlation structure
may be in order. In addition to decaying residual correlations, it's
possible to have subject specific intercepts. Both specifications can
be made via the MIXED procedure in SPSS. Whether these specifications
substantially improve model fit can be examined.

Ryan

On Wed, Dec 15, 2010 at 10:52 AM, PetterBB
<petter.b.brandtzaeg@gmail.com> wrote:
> Hi all, I am studying social implications of media use from 2008 to 2010,
> three time waves. Time 1, time 2 and time 3
>
> I want to check the mean differences on several independent variables, and
> belive Ancova is a could way. Is it possible to use gender and age as
> covriates in Ancova?
>
> Another thing is, can I use time 1 as co-variates in the the second wave
> analysis? How do I do this? Anyone?
>
> Thanks in advance.
>
> best
> petter
>
>
>
> --
> View this message in context: http://spssx-discussion.1045642.n5.nabble.com/Can-I-use-time-and-gender-as-covariates-in-Ancova-tp3306510p3306510.html
> Sent from the SPSSX Discussion mailing list archive at Nabble.com.
>
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