[R] Nested longitudinal data

[Bert Gunter]

Wrong list. Post on r-sig-mixed-models.

-- Bert

On Mon, Apr 23, 2012 at 8:46 PM, arun <smartpink111 at yahoo.com> wrote:
> Hi,
>
> I have some difficulty in figuring out whether I am doing correct or not.
>
>
> A brief introduction about the work: It is a light/dark choice test
> conducted in insect larvae.  The response is binary (0- present in dark
> area, 1-present in light area) and the experiment is run for 15 min, so
> there are 15 repeated measurements per individual larva at 1 min
> intervals.  The factors which affect this study are Strain (2 levels-G
> and S),  wavelength of light (4 levels-blue, green, UV, red), and
> starting response at 0 min (two levels- animal present in dark-D or
> light-L).  This is how I think it is nested.  Strain nested inside
> Wavelength, Subject (individual) nested within strain, Starting response within subject, and time within Starting response.   The data looks like this:
>
>          Number              Wavelength     Strain             Subject           Startingresponse              time (min)
>                 1                        Red              G                   1                          L                               1
>                 2                        Red              G                   1                          L                               2
>             ---------------------------------------------------------------------------------------------------------------
>         ---------------------------------------------------------------------------------------------------------------------
>               20
>  Red              G                     1                         L                                20
>                21                      Red              G                      2                        D                                1
>                 22                      Red               G                    2                        D                                2
>
>             ---------------------------------------------------------------------------------------------------------------
>
>     -----------------------------------------------------------------------------------------------------------------------
>
>  40                      Red               G                      2
>                    D                             20
>
>  -----------------------------------------------------------------------------------------------------------------
>              ----------------------------------------------------------------------------------------------------------------
>
>            121                     Green             G
>    7                           D                             1
>             122                    Green              G                    7                           D                             2
>    ------------------------------------------------------------------------------------------------------------------------
> ---------------------------------------------------------------------------------------------------------------------------
>
> The model I used was:
>
>
> (fm2 <-lmer(Response~Wavelength+Startingresponse+Strain+ time + (time|Subject),family=binomial, data=Behavdat))
>
> I am not sure how to specify the nested structures within the
>  model.
>
> Any help will be appreciated.
> Thanks.
>        [[alternative HTML version deleted]]
>
>
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>



-- 

Bert Gunter
Genentech Nonclinical Biostatistics

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