[R-sig-ME] model specification for repeated measure

[Dot Dumuid]

Thank you!

On Thu, Feb 1, 2018 at 10:54 PM, Thierry Onkelinx <thierry.onkelinx at inbo.be>
wrote:

> Dear Dot,
>
> The specification of your covariates seems reasonable to me. You need
> to check if the Gaussian distribution is relevant for your
> measurements on mental health.
>
> Best regards,
>
> ir. Thierry Onkelinx
> Statisticus / Statistician
>
> Vlaamse Overheid / Government of Flanders
> INSTITUUT VOOR NATUUR- EN BOSONDERZOEK / RESEARCH INSTITUTE FOR NATURE
> AND FOREST
> Team Biometrie & Kwaliteitszorg / Team Biometrics & Quality Assurance
> thierry.onkelinx at inbo.be
> Havenlaan 88 bus 73, 1000 Brussel
> www.inbo.be
>
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>
>
> 2018-02-01 11:37 GMT+01:00 Dot Dumuid <haveaballphysio at gmail.com>:
> > Dear mixed model experts,
> > We have a dataset of older adults. We measured their mental health (MH) 6
> > months before retirement and again 12 months post retirement.
> > At both of these time points we also measured their physical activity
> (PA)
> > (min/day), income (INC) and general health (GH).
> > We would like to create a model that tells us if change in physical
> > activity over the retirement threshold predicts change in mental health,
> > and we'd like to use the model to predict how much mental health is
> > predicted to change when physical activity is increased from perhaps 15
> > minutes to 60 minutes. We'd like to use a mixed model rather than just
> > using change (difference) scores. And we'd like to control for things
> like
> > change in general physical health and change in income.
> >
> > This is what the data look like
> >
> > *ID  time  MH    PA    GH    INC*
> > 01  pre     4      15     56     560
> > 02  pre     5      30     30    1200
> > ..    .....     ..       ..       ..        ...
> > 01  post   7      40     50      50
> > 02  post   8      45     30      0
> >
> > I'm not sure how best to build the model. Something like this?
> >
> > model <- lmer (MH ~ PA * time + GH + INC + (1|participant.ID) )
> >
> > Thank you in advance.
> > Dot
> >
> >         [[alternative HTML version deleted]]
> >
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>

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