[R] question on multilevel modeling

David Duffy David.Duffy at qimr.edu.au
Wed Nov 8 22:19:04 CET 2006

"Christine A. Calmes" <ccalmes at buffalo.edu> wrote:
> [...]  Basically, I am trying to test a
> psychological model in which a person's level of passive, negative
> communication with others in their environment (CORUMTO) on one week
> predicts their level of depression on the following week (BDIAFTER)
> controlling for their level of depression on the same week that that
> they co-ruminate (BDI).  The WEEK variable accounts for the fact that
> there are 7 weeks worth of data in the model and that scores on adjacent
> weeks are more closer related than scores on weeks that are further
> apart.

The alternative would be to fit using the sem package, explicitly
modelling the time-series and estimating the lagged effects of CORUMTO
and BDI -- it may be possible to disentangle the separate effects (a la
instrumental variables type analysis).  This would be easiest if there
are 7 rounds of observations for everyone.  The many time series packages may
also be usable for this.

David Duffy.

| David Duffy (MBBS PhD)                                         ,-_|\
| email: davidD at qimr.edu.au  ph: INT+61+7+3362-0217 fax: -0101  /     *
| Epidemiology Unit, Queensland Institute of Medical Research   \_,-._/
| 300 Herston Rd, Brisbane, Queensland 4029, Australia  GPG 4D0B994A v

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